Rubens Barrichello has threatened to quit Formula One motor racing if he believes the Brawn team is favouring his teammate Jenson Button.
Barrichello's comments, made on television, follows Brawn changing tactics during the Spanish Grand Prix and calling Button in for only two pit stops instead of the scheduled three.
The Brazilian, who completed three pit stops, was leading the race but slipped behind Button when he stopped for his third pit stop. Barrichello finished second behind Button.
So-called 'team orders' are banned in Formula One, with Barrichello having suffered from them during his years at Ferrari as loyal sidekick to seven-times world champion Michael Schumacher.
In the most notorious incident that caused uproar around the world and led to the clampdown on team orders, Barrichello had to let Schumacher overtake and win the 2002 Austrian Grand Prix.
Ross Brawn, who was technical director of Ferrari at the time, denied after Spanish Grand Prix that there had been any attempt to favour Button by switching him to a two-stop strategy .
Button later said he had not requested the switch to a strategy that he had expected would in fact favour his team mate, and Barrichello made clear he was not accusing anyone.
Barrichello, who will be 37 during the next Monaco Grand Prix at the end of the month, has not won a race since he was at Ferrari in 2004 and many in the sport had written off his chances of competing this year after Honda's dismal 2008 season.
Brawn's emergence from the remains of departed Honda threw him a lifeline but he has found Button as hard to beat as Schumacher was. Button has won four of the five races so far while Barrichello has two second places.
