Jenson Button has said that McLaren's pace has been "hurt" by the hot conditions at Sepang ahead of this weekend's Malaysian Grand Prix.
The team had both cars in the top three at the opening race of the season following Daniel Ricciardo's disqualification from the Australian Grand Prix.
The 2009 world champion told Sky Sports News: "Our pace isn't there this weekend so far. The hot temperatures hurt us quite a bit I think because we're not quite so strong in high-speed corners, and it just exaggerates the issues you have. Degradation's always worse with the hot conditions.
"So we're finding it tough out there at the moment and hopefully with the cooler conditions on the weekend and a few set-up changes we can be a bit more competitive.
"[Tyre wear is a factor], but I think our outright pace isn't there either. Not just compared to the Mercedes but compared to half the field really. So there's a lot we need to do for tomorrow and qualifying."
Button was eighth in the second practice session for Sunday's race, while teammate Kevin Magnussen was 12th.
