Alonso faces difficult fight for title - Button
Alonso is the only driver to win more than two races this season and currently leads the title chase by 40 points from Mark Webber. But despite Alonso's success, his Ferrari team has had a tough start to the year and has struggled to match its rivals on outright pace.
"The team [Ferrari] have done a great job to get the points they have, but I don't think they've really had the speed," Button told Sky Sports News. "They are going to manage it well, they are a great team and Fernando is a great driver. But it's tough when you see other teams winning races consistently and I think that might be happening over the next few races."
Button, who is 88 points off Alonso, is confident he has got over the set-up woes which resulted in a run of poor performances between the Spanish and British Grands Prix.
"I tried a few things with the car and it was the wrong direction - that was around Canada [GP] time," he added. "But we've come back from that and at the last couple of races I've been a lot happier. So the general car is good and the improvements that we've put on it at the last two races have been great and I think we're very good at getting everything together at the moment."