The Frenchman has struggled to match the pace of team-mate Kimi Raikkonen this year, and has been beset by set-up struggles.
Grosjean felt he had made some progress after qualifying sixth for the Chinese Grand Prix, but he dropped to ninth in the race.
Lotus owner Gerard Lopez admits that Grosjean has not produced the pace he had last season, but he sees no reason to worry just yet.
"The performance is good," said Lopez. "Last year everybody was complaining that he was not a consistent driver, but he is. He was just caught out in a number of events.
"He is below the pace he had last year, but there is no reason why he cannot drive like that again."
Lopez believes that the key to getting Grosjean back to his best is in ensuring he gets more on top of his car throughout practice.
"He is usually a day or half-a-day late compared to Kimi, so by the time qualifying is on he is not in that comfort zone," he said.
"He needs to get back to that and, if he does that, I have no doubt he is top five material."
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- Kimi Raikkonen