First, Nick Heidfeld was axed, then doubt was cast over the likelihood of Robert Kubica returning to the team - and now it appears that Vitaly Petrov's seat at Lotus Renault GP is similarly at risk, judging by remarks made by the Enstone-based outfit's managing director Eric Boullier.

Last week, Boullier issued Kubica a deadline of the end of next month to prove that he is fit and competitive enough to rejoin the grand prix grid following the high-speed rallying accident back in February that ruled him out of the F1 2011 campaign, reasoning that whilst he 'really likes Robert and it will be good to have him return', at the same time, he 'needs to look after the interests of my team' and 'needs to know if he can do it' still [see separate story - click here].

Petrov has insisted that 'my contract is safe for next year', but now it seems that the Russian may not be quite as secure as he believes either, with German magazine Auto Motor und Sport predicting a Bruno Senna/Romain Grosjean line-up at LRGP in 2012 instead - and Boullier has done little to dampen such speculation, telling the Daily Mail that 'you have contracts, but there are some exit clauses for every party'.

Although Petrov has improved considerably this season following a promising but patchy rookie campaign in the top flight in 2010, the 27-year-old's chief attraction remains his ability to unlock lucrative sources of untapped sponsorship income back in his homeland - but it is understood that Senna could be an even better bet on that front, and the Brazilian has impressed during his two race appearances for the team to-date this year.

Boullier has made little secret of his desire to find newly-crowned GP2 Champion Grosjean - whom he manages - an F1 cockpit, but insists it is 'too early' to think about a race seat for Senna in 2012. The former HRT ace, though, knows what he needs to do.

"The best way for me to be racing next year is with the results on the track," he acknowledged. "The objective is to keep having strong results and fix my place in F1, and the key to that is to keep improving and learning."