Is Ferrari as dangerous as Mercedes thinks?

Since it suffered defeat at the hands of Ferrari in the humidity of Malaysia, Mercedes has been fretting about the possibility of the Scuderia out-foxing it again on race day.

Last time out in China, Lewis Hamilton drove a go-slow race at the front to protect his Pirelli tyres, which put team-mate Nico Rosberg under pressure and allowed Ferrari (which was clearly second best on pace) to get much closer than it otherwise might have done.

After the first day of running in Bahrain, Mercedes again leads the way on outright pace (by half a second), with Nico Rosberg edging out Hamilton by a tenth on a track at which the German is always strong. But the recent concerns about Ferrari being "dangerous" and "worrying" over the longer runs have again reared their head.

So does Mercedes have genuine cause to be concerned about the threat from the red cars around the 3.4-mile circuit, or is this merely more of the paranoia we witnessed in China, where Mercedes probably should have won more easily than it did?

Looking at the laptimes, the pattern looks similar to the one we saw in Malaysia - with Mercedes enjoying a significant advantage over a single lap, but Ferrari stronger over a stint.

But - frustratingly - both Ferrari drivers made substantial errors on their quickest laps early in FP2, which suggests they could be much closer over one lap than the 0.527s gap we saw between Hamilton and Kimi Raikkonen in practice two.

Sebastian Vettel should have set a much faster time than the 1m35.277s he managed, but he ran wide at the final corner on his quickest lap, while Raikkonen was only a tenth faster than Vettel, having opted to complete a second quick lap on the soft tyre after messing up his first.

So there is every chance that Ferrari could be closer on one-lap pace than at any point so far this season, but with the caveat that Mercedes usually finds significant time once it switches to its aggressive qualifying engine maps on Saturday.

As far as longer running goes, Mercedes again decided to split strategies across its two cars here, no doubt hoping to cover all bases after being so comprehensively out-manoeuvred by Ferrari in Malaysia, when Hamilton endured a troubled Friday.

If the race ran in daytime temperatures, Ferrari might be even better off © XPB

Pirelli calculations suggest a large gap between the soft and medium tyre on outright pace (around two seconds), which means the soft rubber will be the tyre of choice for Sunday - provided it can be made to last long enough (around 18-20 laps) to make the finish on two stops.

Hamilton did most of his running on the slower medium tyre, but his average pace across an 11-lap stint (1m40.991s) was only half a second slower than team-mate Rosberg (1m40.445s), who was charged with running the soft tyre.

Most worryingly for Mercedes, Vettel's average pace on the soft tyre (1m39.499s) was almost a full second faster than Rosberg's - the largest long-run gap Ferrari has enjoyed on a Friday so far in 2015. But - and it's a massive but - Vettel's 'long' run was only eight laps, significantly shorter than Rosberg's. So there's every chance that substantial gap is much closer in reality.

Raikkonen ran the same programme as his team-mate (eight laps on the soft), but was less consistent and consequently around three tenths slower on average than Vettel.

Of course, everyone wants to know whether all that means the Bahrain Grand Prix will likely play out the same way Malaysia did, meaning Formula 1 is set for another thrilling battle between Mercedes and Ferrari.

On the face of it, this circuit should play more to the strengths of the SF15-T than Shanghai, where Mercedes was dominant - even if it didn't fully flex its muscles. In Bahrain the emphasis of tyre management switches back to the rear axle, as it was in Malaysia, which is good news for the Tifosi.

The big potential spoiler for Ferrari hopes is the fact the Bahrain GP will take place under cover of darkness, which will mean significantly cooler conditions than we witnessed in Malaysia. The emphasis of rear tyre management is placed on pure traction at this track, with less concern about the lateral cornering forces that are more prevalent at Sepang.

Track temperatures in Malaysia soared above 60C, but Friday's representative running in Bahrain (the daytime laps in practice one are irrelevant for a night race) took place on a circuit that reached just 36C - around 5C lower than we saw on Sunday at Shanghai.

The upshot is that Pirelli is expecting a straightforward two-stop race - similar in strategic terms to what we saw in China, which should play into Mercedes' hands if it can (as it should) gain the advantage of pole position on Saturday and a strong start on Sunday.

Rosberg sees Sakhir as a track where he can strike back at Hamilton © XPB

"Wheelspin is the risk you have [here]," explains Pirelli motorsport director Paul Hembery. "When we came here with the new cars, for the beginning of last season, we saw the cars sliding substantially. It's interesting to see them now - they're back on rails again.

"The teams will have worked on set-up and mapping of how the torque [from the engines] is applied. That has been a big improvement since we came here 18 months ago [for 2014 pre-season testing].

"Some of our guys wanted to come here with the super-soft - it [Sakhir] is more akin really to a street circuit from some points of view; in a way Abu Dhabi is too: smoother surfaces, braking loads, traction - characteristics you tend to see in street circuits.

"Here if we had raced in the daytime in 55C then you would have probably had a Malaysian-type situation with some teams doing a two-stop and some needing to do three, simply because the thermal effects would have been so dramatic.

"It [the track temperature] dropped from 55C to 35C [from practice one to practice two]. Today you sat outside you were sweating, now [in the evening] you could put a jacket on!"

Hembery's point about the tyre compounds is crucial. Given the conditions we are likely to see on Sunday, only use of the super-soft and soft tyres would likely introduce the sort of strategic variation that could have given Mercedes a serious headache at this race. A more conservative choice from the tyre supplier should play into the hands of those operating the silver cars.

However, we simply cannot ignore the pace Vettel showed on his long run here. If Ferrari can translate a significant fraction of that 1s advantage on race day then Mercedes will be under serious pressure from behind - far greater than it faced in China.

Given the SF15-T clearly holds a tyre-management advantage over the W06 at present, if Vettel or Raikkonen are able to unleash extra pace once the Mercedes pit, they could conceivably gain a race-winning edge. Certainly Mercedes will not be able to afford the go-slow approach it utilised in China, where Ferrari was not really fast enough to capitalise on that conservatism.

It looks as though Mercedes will have to genuinely out-race Ferrari to win here, which could potentially mean sacrificing the slower of its two cars strategically to ensure the other one wins.

If he can't turn the tables on Hamilton in qualifying, Rosberg will likely end up being the driver sacrificed in that scenario. So unless Ferrari's Friday pace is overstated, or Mercedes has something in reserve we haven't seen yet, he is probably right to be worried by the threat from Maranello.

Whether Rosberg can carry that tenth-of-a-second advantage he holds over Hamilton - which did owe a little to the champion locking up on his best lap - from Friday through to Saturday could prove more crucial than anything else in the end.