Sergio Perz needs to stop being "very polite" and "toughen up", according to his team boss Martin Whitmarsh.
The Mexican driver recorded his second grand prix outside the points for McLaren in China on Sunday, the culmination of a disappointing weekend
Hitting the barriers twice on Friday, Perez admitted that he's "not very confident" with his MP4-28 as it is an "inconsistent" car.
That showed in Saturday's qualifying where he finished 12th while not faring much better in Sunday's grand prix where he was 11th.
"I think he's been very polite so far this year. He needs to toughen up," Whitmarsh told The Guardian.
"He's been generous in allowing people past him.
"He's still a very young guy in a big team with lots of expectations so you're under a lot more scrutiny and it's tougher.
"And he's got a team-mate [Jenson Button] who's doing a great job, so there's some pressure there, and this won't go down as his best weekend, of that I'm sure."
Perez did show some aggression on Sunday as the 23-year-old ran Kimi Raikkonen wide when the Lotus driver attempted to pass.
That, at least, went down well with his McLaren team boss.
"Sometimes you have to be robust and have elbows. And I think he was robust," Whitmarsh said.