Rival teams are preparing to engage in a bidding war for current Formula 1 World Championship leader Jenson Button's services for 2010, it has emerged - with the Brawn GP ace said to be 'at the top of many people's lists' as his stock has inexorably risen just as that of compatriot Lewis Hamilton has slumped.

With five victories to his name from the opening six races of 2009, Button heads into the Turkish Grand Prix this weekend 16 points clear of team-mate Rubens Barrichello in the title standings and a full 28 points ahead of the leading non-Brawn challenger, Red Bull Racing's Sebastian Vettel.

What makes the 29-year-old's success all-the-more outstanding still is that barely two months prior to the start of the season, he had not been expected to feature on the grid at all, following Honda's sudden and shock withdrawal last December.

A Ross Brawn and Nick Fry-led management buy-out saved the Brackley-based outfit at the eleventh hour, but still little was anticipated of a team that over the previous two seasons had notched up a scant 20 points - less than a quarter of its current tally of 86 just over a third of the way into the present campaign - and a solitary podium finish. The turnaround in fortunes has been little short of remarkable.

Button even agreed to a significant pay cut in order to help keep Brawn GP afloat - reputedly sacrificing two-thirds of his ?8 million-a-year salary - but predictions are that he will likely be earning closer to the ?20 million mark next year. Though the team has made no secret of its desire to retain its star driver until the end of his career in the top flight - with CEO Fry admitting that 'he's done a great job and later in the year we will sit down and have a discussion' - with the long-term commitment and financial input from Richard Branson's Virgin Group still uncertain, the question mark is over whether they can afford to keep him.

"There are going to be quite a few seats open next year," one team chief told the Daily Mirror, "and Jenson is going to be at the top of many people's lists. How could he not be after his performances in the last few races?

"Any question marks that were remaining disappeared after his pace in Monaco. It wasn't just that he won it; it was that he started the weekend with a car he was far from happy with and developed it into a winning car. Apparently, even Rubens Barrichello was surprised with the pace he got out of the car right at the end of qualifying.

"We are certainly interested in his services and have made that known - we'd love to have him in our car next year - but we'd be daft to assume we're the only ones. A lot of people like the humble way he has carried himself at a time when he could have crowed and told his critics 'I told you so'."

Ferrari has been mooted as a possible destination - with former world champion Kimi Raikkonen repeatedly failing to justify his ?35 million pay cheque - as has McLaren-Mercedes, where fellow Finn Heikki Kovalainen has generally failed to step up to the plate against Hamilton. One factor in Brawn's favour, however, is that for all that Button was pilloried earlier in his F1 career for chasing big bucks rather than a competitive car, he now has his eyes firmly on performance rather than pounds - and there is no better-performing team at the moment than his current employers.