Hamilton's warning shot amid Mercedes' quiet start

Had George Russell not emerged to complete 23 laps shaking down the Williams on Wednesday, Mercedes would have ended a day of testing as the slowest team for the first time in the V6 turbo-hybrid era.

In what's proved to be a quiet start to pre-season for Lewis Hamilton and Valtteri Bottas, they finished 11th and 12th on the timesheets. Bottas is 15th for the week overall, while Hamilton is 17th. Only the troubled Racing Points and the largely absent Williams drivers sat behind them with one day of the first week of testing remaining.

Mercedes hasn't slipped to the tail of the field and Hamilton's title hopes aren't in tatters. No amount of extrapolating the data from the first three days could back up an argument that they had. But there have been questions over why it might be keeping its powder this dry, especially as last year it did show performance earlier than this.

It might be a quiet start but there are already indicators of what we should really expect. To start with, the first signs of Mercedes' true pace have begun to emerge. Second, Hamilton looks like he has answered the biggest question mark over him for 2019.

Sticking with Mercedes for now, on Thursday morning Hamilton set its best time of testing so far, on a day the team set out to focus "a little bit more on performance".

More relevant are the race simulations Hamilton and Bottas completed on Wednesday, something Ferrari has not managed yet. They were both interrupted - Hamilton, seemingly, by a lock-up that forced an extra pitstop and Bottas by a red flag - but their 60+ lap tallies yielded extremely close averages. Both drivers were using C2-compound Pirellis and Bottas had the edge with a 1m23.358s, while Hamilton was just behind on a 1m23.754s.

Initial, tentative pace comparisons from Wednesday suggest that it's close between Mercedes and Ferrari. Vettel's longest run on the same day was a stint of 17 flying laps on softer C3-compound tyres that averaged 1m23.658s.

Hamilton pledged to become a "different athlete" - and it looks like he has done exactly that

While the two teams' performance levels will become clearer next week, unsurprisingly the picture is not quite as clear as 'Ferrari looks great and Mercedes is struggling for some reason'. Something emphatic to emerge from this week, though, is more specific to Hamilton and the early warning shot he's fired off-track.

F1 has introduced an 80kg minimum weight for drivers instead of incorporating the driver into the total weight limit of the car. This will reduce the disadvantage faced by taller and heavier competitors, but it also reduces the need to have an aggressive diet to save weight.

Hamilton said last year he was relishing the chance to use the new rules to bulk up. He pledged to become a "different athlete" - and it looks like he has done exactly that. Mercedes team boss Toto Wolff said "he came back stronger and more muscly than before", and that testimony proved correct when Hamilton arrived at the circuit this week. Put simply, he's filled out.

Hamilton's increased muscle mass is visible. He proudly said his improvement was "a lot more than that" when told by Autosport that other drivers have reported a 1-2kg gain in muscle mass over the winter.

"But I'm still within the limit, so I'm good," the smiling Hamilton added. "Every year, the fundamentals are the same, trying to reach a similar target every year, so to have that bar lifted and to really dig deep into other elements of training has been quite an exciting challenge.

"Every year when you get back into training, it's painful. But I tried different methods, worked with several different people for once. I don't have a trainer but I've gone to work with people I know of, or got in touch with, to try different things throughout the weeks.

"And I get to take that throughout the year. Deep-rooted, core-wise, I feel stronger than I've been in a long time."

Hamilton was a busy man in the off-season, trying a range of activities from surfing to martial arts. He described it as wanting to explore "different disciplines, different challenges that use different parts of the body".

It's more than just a physical thing, though. Wolff says Hamilton is in "a super mental state, the best I've seen so far" and Hamilton says he is "definitely happier".

After securing a fifth title, the difficulty for Hamilton to reset and go again should not be underestimated

The days of missing meals to hit a strict weight limit led to lapses of energy, and an unhealthier state. Now, Hamilton says he is eating more, sleeping better and has more energy.

This should serve as a warning to his rivals. Hamilton is at his very best when he's happy, and he seems to get happier every year with Mercedes, which lets him pursue his own personal projects away from the track.

It's part of why Hamilton reached a new peak in 2018. Against Mercedes' toughest challenge yet he matched his personal-best haul of 11 wins in a season, psychologically bested Vettel again and produced some immense performances on the way.

The big question mark hanging over him at the end of the year was how does he raise his game again? Motivation and standards can slip during a run of success.

After securing a fifth title, the difficulty for Hamilton to reset and go again should not be underestimated, especially knowing young guns such as Charles Leclerc, Vettel's new team-mate at Ferrari, and Red Bull-Honda's leading man Max Verstappen would offer new, energetic challenges.

Hamilton has not let that happen. His awareness of the emerging threats, as well as his overall happiness, is a key part of that.

"It is an exciting year, particularly with the drivers moving around and you have a lot of young drivers moving around," he said.

"I am definitely interested to see their progression and the pitfalls that they happen to come across, which every driver does, and how they spring back from it.

"And naturally I get to race against some of them as well. I feel stronger and fitter than I have ever been, all round, so hopefully that reflects in my driving."

If it does, and the car is good enough, Mercedes may become the first team to win six titles in a row. Hamilton says he will not let that be a distraction though.

Instead, he wants Mercedes to attack like it's aiming for its first championship.

"We're always driven to do something new and break boundaries," he said.

"But we're fully aware of the work it will take to deliver something like that. By no means will it be, 'Oh yeah, we're going for the sixth', like it's a relaxed thing. It's not like that. I'm not even focusing on that.

"It's a new season, a new year, a new chapter. We have to approach it like it's our first. We're going for number one. That's how I approach it."

When Hamilton aimed for number one with Mercedes the first time around, in 2014, he achieved exactly that and went on to win 11 races.

Ferrari's strong start, an apparently revitalised Vettel and the possible threat of Verstappen's Red Bull-Honda means nobody is expecting that to be repeated this year.

But Hamilton and Mercedes are F1's benchmark partnership for a reason. One half of that looks more ready for a title fight than ever. He just needs confirmation his car is up to the task as well.