Will F1's most volatile rivalry explode in 2018?

Rivalries add a glorious edge of grit and fire to Formula 1, beyond the simple pleasure that comes from masters of their craft expressing their talents on track. How dull the first three seasons of Mercedes' F1 domination would have been had relations between Lewis Hamilton and Nico Rosberg not disintegrated so spectacularly amid all the collisions, suspicions and recriminations.

With that dynamic obliterated by Rosberg's retirement, harmony now reigns at Mercedes - so long as Valtteri Bottas remains such a sanguine team player and Mercedes does nothing to upset Hamilton's newfound equilibrium. But the whiff of interpersonal controversy still coats the Silver Arrows from afar, even though Rosberg is no longer on hand to help give it form within the works team.

The intra-team rivalry with most edge in F1 these days no longer plays out at the front of the grid, between a hauled up by his boot straps lad from Stevenage and the cosmopolitan son of a world champion born into motorsport's elite. But it still belongs to Mercedes - powered by its engines, with one of its own at the centre.

Esteban Ocon and Sergio Perez collided in three races last season, as Mercedes junior Ocon fought a battle for superiority with Force India's established midfield ace. That's prolific enough to rival anything Hamilton and Rosberg managed in any one of their bitter battles for the world championship.

Of course, the stakes are much lower for Ocon and Perez, the profile too, but there is still much riding on what happens inside Force India over the next 12 months. There has been ever since Force India elected to take Ocon under its wing at the end of 2016, after Nico Hulkenberg jumped ship to Renault.

"It's something our eyes were pretty open to at the start of the year," says Force India chief engineer Tom McCullough, who has been at the forefront of dealing with his team's new driver dynamic over the past year or so.

"We were not naive to it. We sat down and discussed the fact that when you bring a new person in, at a different stage of their career, you realise they're both trying to prove themselves.

"Because Sergio and Nico were at a similar stage of their careers previously, there wasn't quite that need to maybe establish themselves over the other one as much.

"It's easier for us to have one quicker and one slightly slower. We could have chosen that if we wanted to and we didn't. We went for what we thought were the best drivers we could get, and that's for us to manage."

There was no hint of trouble to begin with, as Ocon adjusted to his new environment and built on the limited experience of that half-season with Manor. As early as the fourth round, in Russia, Ocon was right with Perez in qualifying.

In Spain, Force India felt Ocon would have qualified ahead without a mistimed press of his DRS button. A crash dented Ocon's confidence in Monaco, but he was back on form in Canada, which is when things began to get heated.

"At the start of the year it was important in each of their heads they came out on top of the other guy," explains McCullough. "The pressure was there on Sergio to not be beaten by the young up-and-coming guy; for Esteban, he's trying to show his backers Mercedes and the rest of the world that he's got the ability to be better than the established driver. So, it was always going to be fierce.

"Once we got to the stage in Canada where they were quite close to each other, to maximise the points for the team we split the cars strategy-wise. We operated totally within our standard way of operating - where the lead car gets priority - but if we get to a point where we think the lead car isn't able to challenge the guy in front, and the car behind potentially can, then we do discuss switching the cars to give that a go, and if it doesn't to switch back - all the usual stuff.

"We gave - and it was a mistake really from our side - Sergio the message. We'd been asking Sergio to manage his tyres in the earlier part of the race and we said 'from now on, the tyres are safe to the end, from our data and the way you've been driving them, so we want you to push on and have a go and if not then we're going to have a look at switching the drivers'.

At Spa, Ocon accused Perez of being unprofessional and "risking our lives for nothing". Say what you will about Hamilton and Rosberg, their war of words never got that heated

"The way that message was then interpreted, by the press and the commentators, who were trying to ham up a story, they tried to say Sergio was disobeying team orders. He wasn't at all. The instruction was 'now push, your tyres are safe, have a go at him, if you can't have a go at him then we'll look at switching the drivers'. Sergio obviously was saying 'yeah, leave us! Don't worry, I'm going to go for it'. And he did. He picked up his pace from then on and got closer.

"It wasn't enough to overtake. Everyone's got their opinions on whether, if we'd swapped the cars, Esteban would have overtaken or not, but fundamentally [Daniel] Ricciardo [who the Force Indias were chasing] was managing [his tyres] as well. We didn't feel it was going to happen, so we didn't switch the cars.

"At the end of the race, when Esteban was trying to overtake Sergio and there were a few aggressive defending manoeuvres, which were all legal manoeuvres - we expect you to race hard with your team-mate; we don't expect you to drive into your team-mate - to us that was fair driving."

But what happened next time out in Baku looked far from fair, as Ocon and Perez banged wheels then collided spectacularly at the exit of Turn 2 while battling for position. Ocon choked off the space available to Perez on the exit with disastrous consequences, robbing Force India of a large double points haul and, potentially, a double podium finish.

"The final contact I don't believe was intentional by Esteban," argues McCullough. "I think it was a frustration coming out of the corner before - Sergio was on the back foot, he'd been overtaken, he was a bit offline; Esteban had gone up the inside, Sergio had closed the door on him, and they did make contact there.

"If you look at the data, the minute they make contact Sergio lifts and turns right. A driver doing that on purpose wouldn't do that. Esteban is going up the inside and is thinking 'bloody hell - the guy's driven into me!'. I think all Sergio was doing was trying to be defensive. He barrelled into the corner, Esteban really pushed out hard, nearly making contact, banging on the way in; but in the end the corner was his and he just didn't give Sergio enough room.

"That was a mistake, and Esteban understood that. He had the overtaking manoeuvre done and he thought he was past. He was quite surprised, I think, when Sergio was still there. You can argue forever whether he should have been there. Drivers aren't going to lift, but in that situation, especially when it's your team-mate, you've got to give them that little bit of room."

Force India now seemed trapped in the very same quandary that used to agonise Toto Wolff so acutely - how to allow your two drivers to keep racing without that leading to further unwelcome incident. Wolff tried limiting strategic variance between Hamilton and Rosberg, opening it up again, and even threatened to bench them at one stage after they repeatedly misbehaved. But Mercedes never had full control of its protagonists, no matter how hard Wolff tried.

A few more races passed without further trouble, until two scary high-speed collisions occurred at Spa on the run to Eau Rouge, after which Ocon accused Perez of being unprofessional and "risking our lives for nothing". Say what you will about Hamilton and Rosberg, their war of words never got that heated.

"Of course drivers see everything from their own perspective - 99.5% as opposed to the other half a percent - and unfortunately at Spa, again that was a mistake from our side," concedes McCullough.

"Strategically, the lead car was Esteban in that race - he was quicker. With Sergio having to serve his penalty, we expected Esteban to be out in front [after the stops]. He did actually come out the pits in front, but on the run up the straight it was too close - Sergio had obviously pushed very hard to try to overtake Esteban, so he got a run, DRS and overtook him.

"From our side, what we were trying to do was push Esteban to clear another car, so it was all done for the right reasons, but we should have pitted him a lap earlier and that [incident] would never have happened."

"What happens next will be interesting to see. Can Esteban go up another level? Can Sergio go with him? I'm looking forward to how it all rattles out" Force India chief engineer Tom McCullough

It's clear to see how easily and inadvertently a team can make its own situation worse - even with the best of intentions. Mercedes laid down rules that were designed to ensure each of its drivers was treated fairly, only to later see those guidelines abused or flaunted entirely. Often, Mercedes was simply playing catch-up as the drivers found new ways to turn the screw on each other.

Mercedes threatened Hamilton and Rosberg with the sack should they have repeated their Spa collision of 2014. Things quietened down, only for the two to start hitting each other again in late-2015, before receiving further threats from the team in the summer of the following season, after two more costly collisions. Keeping a lid on such intense rivalry is fraught with peril.

Mercedes never went as far as actually banning its drivers from racing, a commendable approach for the good of the championship and its TV ratings. But Force India, interested only in its constructors' placing and nothing else, could afford to be stern.

"We'd spoken to the drivers about 'no contact' policy and said 'you've both got to drive in a way that you make sure you don't hit each other'," McCullough adds. "That didn't happen, so we took them both aside and said 'OK, you've not done what we asked for, so we're going to change our rules now, which is 'you're not allowed to race each other'.

"Strategically, for a few races we were quite careful to make sure we had a bit more margin. If we had a slow stop, like we did in Spa, all these little things they all add up and just kick you when you're down.

"Generally, on the pitwall, the way we operate - because we're not fighting for drivers' championship points, we're fighting for constructors' - we're open with our drivers and it's all about trying to maximise the team points.

"Drivers can sit and say they agree with that, but they've obviously got only one ambition, which is to maximise their own points, which is fair enough. So, there is always that balance, but from the team's side we've also got to leave a bit of margin to make sure we don't create situations when the drivers are that closely matched.

"A lot of people from rival teams have said to me what a disaster it's been and how badly it's been managed, but looking at other teams - some with one very good driver and one very bad driver - I think the slight issues we've had with the two of them establishing themselves [has been worth it]. We had a slightly difficult phase, but they were nice problems to have."

After a calmer conclusion to 2017, Force India now seems to feel Perez and Ocon have earned the right to be free to race each other again. Perez is already pushing the team to relax its rules, but that presents fresh potential problems for 2018.

Perez knows the time is now to prove he deserves another shot at the big time after his abortive spell at McLaren in 2013. He has rebuilt his reputation and will be eyeing the seat Kimi Raikkonen is expected to vacate at the end of the season.

Mercedes is basically telling Ocon he has to defeat Perez this year, while avoiding further incident, to prove he is worthy of promotion to the big league further down the road.

While containing that potentially explosive mix of individual, personal ambition, Force India will need to fend off renewed threats to its standing in the constructors' championship.

McLaren-Renault will undoubtedly be stronger this year, the works Renault team too, while Williams has supposedly built a much more aggressive car as it bids to reclaim the ground lost to Force India over the past couple of seasons.

"What happens next will be interesting to see," says McCullough. "Can Esteban go up another level? Can Sergio go with him? That's the bit that's always hard to know.

"The really good thing is now, having been through all that and seen how the team has reacted, the drivers have really changed - it's a better relationship than they had even at the start of the season.

"I'm sure all they want to do is beat each other, and I'm sure they don't go out to dinner together too often, but the way they work, the openness between the two sides from the engineering side - we're always really strong on that anyway - the drivers realise there are no games to be played. Everything is on the table and they're getting on well together and working well together.

"So often we look at the overlay in the data and there's nothing in it between them. Personally, I'm looking forward to seeing how it all rattles out, because they both realise each other is bloody good!"

And that's why things won't necessarily get easier, even with the benefit of hindsight and that necessary re-enforcement of the team's core values. As Mercedes so often found out, such intense rivalries are always bubbling just under the surface, waiting for the single flash point needed to turn calm back into chaos.