I don't think we'll be fighting at front this weekend, says Jenson Button

McLaren's expected improvement at the Chinese Grand Prix fell flat after disappointing performances in Friday practices, with Jenson Button saying the car's problems have not been solved.

The three-week break since the previous Formula One race raised hopes that the team could fix the teething problems with its redesigned car, but there was little indication of improvement with Button almost a second off pacesetter Felipe Massa, and teammate Sergio Perez a further half a second back.

Button said the upgrades brought to China were less than what was needed to be able to fight for a podium on Sunday.

"They're perhaps not as big a step forward as we'd expected - the issues with the car are still there - but the car does feel a little bit better," Button said.

"I don't think we'll be fighting at the front this weekend."

Button suffered a puncture during the second session to further compromise the practice program.

Perez, who could not have anticipated the early season struggles when he moved across from Sauber, had an even more difficult day, twice going off the circuit in the morning session.

The second incident saw him fail to negotiate the sharp left turn on the road leading to the pits, going nose first into a tire wall and ending up in the same gravel trap which claimed his McLaren predecessor Lewis Hamilton in 2007, ending his rookie title challenge.