Jenson Button has warned that Sauber driver Kamui Kobayashi will be a factor in the Chinese Grand Prix.
Kobayashi starts the race from third on the grid and his practice pace suggests that he can maintain that for into the race.
While Button, who starts fifth, expects Mercedes to drop back despite Nico Rosberg and Michael Schumacher starting on the front row, he is less confident about being able to get ahead of the Sauber.
"It's not easy starting from where we are, but most of the cars in front are ones that we are quicker than in the race," said Button. "The one that is unusual is Kobayashi.
"Their [Sauber's] pace seems very good on long runs. I think he's going to be pretty tricky tomorrow."
Button is hopefully of being able to fight his way into contention for victory and predicted that the early stages of the race will be dramatic because of the unusual qualifying order.
He suspects that he and team-mate Lewis Hamilton, Kobayashi and the Lotus of Kimi Raikkonen could have a pace advantage over the Mercedes once the race is underway.
"It's a completely different grid to what we have seen so far, so it will be an exciting first few laps," said Button. "We have Kamui just in front so that's going to be a lot of fun.
"You'd probably say that the Mercedes race pace is not as good as those behind them."