Jenson Button is backing Ferrari to fight back next season and Mercedes GP to join the hunt for the World title.
This year's campaign saw Red Bull Racing and Sebastian Vettel run away with the titles while Button and his McLaren team were left to pick up the scraps, finishing runner-up in both Championships.
However, Button reckons next season there could be as many as four teams battling at the front as he expects Ferrari to return to form.
"They are strong as a team, especially with Fernando Alonso at the top," said the Brit, who added that Mercedes GP could "possibly" enter the fray as well.
Speaking at the Race of Champions in Dusseldorf, Button shared his thoughts on his 2011 campaign, saying: "I have really enjoyed this season and I have a car beneath me that I have had a big part in.
"It was good, but not quite good enough. We did not have the speed to challenge Red Bull and that is a problem. If you don't challenge a team, they do not make mistakes."
