Ross Brawn has warned Michael Schumacher's F1 2010 rivals that the record-breaking German returnee is 'very intense', 'very passionate about racing again', 'working hard' and 'pretty close to what I remember' from the pair's glory days together at Benetton and Ferrari between 1994 and 2006.

Over that period, Brawn helped to expertly guide and engineer Schumacher to each and every one of his seven drivers' titles in the top flight - and as he bids now to conquer an incredible eighth at the age of 41 and following a three-year absence from active competition, the Kerpen native has made it clear that he would not have followed through with what is being described in some quarters as the greatest comeback in sport for anybody else.

As the most successful driver in F1 history readies himself to take on the current crop of young guns of the likes of Lewis Hamilton, Jenson Button, Fernando Alonso, Sebastian Vettel and his own highly-rated Mercedes Grand Prix team-mate and compatriot Nico Rosberg, he is, Brawn confirms, on it again.

"Michael has been very intense in terms of his approach," the Englishman told the BBC. "He's pretty close to what I remember. He stopped because he was tired of F1, but that's gone now. He's very passionate about racing again and is working hard with Nico to improve the car. He's got to start getting back into the groove, but I don't think Michael will be the issue - we've got to get the car a little bit better.

"Until we get Michael and Nico on-track at the same time it's impossible to judge between the two of them. They both look very good. You don't want to see either driver trailing behind, and judging from the tests on different days they are close. I don't think they know where they are, because conditions and tracks make comparisons different - but I think both drivers are looking competitive."

The comment about improving the car refers to the fact that whilst it remains fiendishly difficult to properly ascertain the true pecking order amongst the leading contenders heading towards the curtain-raising Bahrain Grand Prix at Sakhir in less than a fortnight's time, the general paddock consensus is that Mercedes is slightly trailing its chief world championship rivals Ferrari, McLaren-Mercedes and Red Bull Racing.

In Schumacher's hands, the Stuttgart manufacturer's challenger lapped the slowest of the four on the final day of pre-season testing in Barcelona on Sunday - albeit by less than three tenths of a second - and Brawn concedes that the team will not begin 2010 with the same kind of performance edge as it had in 2009, what would prove to be the key to dual title glory as Button triumphed in six of the opening seven grands prix to establish an ultimately unassailable lead. But then nor, the 55-year-old opines, will current pace-setters Ferrari.

"You saw at the beginning of testing that Ferrari were quite dominant, but based on this test the teams are all pretty close," he mused of the four-day outing around the Circuit de Catalunya, whilst forecasting 'a super-hard battle' ahead. "Overall, we are very pleased with the progress made with the MGP W01 and the integration of Michael and Nico into our team.

"In performance terms, we are not quite where we want to be yet but then again we are not far off - just a few tenths - and we're close enough to be within reach and there or thereabouts [in race trim]. In testing, it is always difficult to be precise about your position relative to the competition because you don't really know what anyone else is doing.

"We have our complete upgrade package due for the first race in Bahrain which should bring further improvements, and I hope that makes the difference. The balance is getting better, and set-up and obviously efficiency count, and the upgrade should bring predominantly an efficiency improvement and therefore a performance improvement.

"There are probably only two or three times in my career that I started a season with the same performance advantage as I had last year. I just think it will be a super-hard battle this year, bit-by-bit, whereas last year we had a huge advantage and it was a question of hanging onto it as long as we could. We are close enough to have a go at [winning races], but obviously we're not enjoying the same situation as we were last year."

Those thoughts were corroborated by Schumacher, who after admitting that Mercedes is presently 'not perfectly in the position we want to be', subsequently acknowledged that 'you have to win by the end of the season, not the beginning' [see separate story - click here].

"The four testing days in Barcelona have helped us to make significant progress with the MGP W01, and I am feeling quite confident for the start of the season," the 91-time grand prix-winner underlined. "It is always difficult to read too much into testing but, knowing our programme, it is fair to say that the times did not always reflect the true picture.

"We have worked through many set-up and development evaluations this week and gained valuable information to study before Bahrain. We are heading into the first race with a good feeling, and we know that we will have our upgrades there - but most of all we know that our prospects for even the first races are looking very reasonable now."