Jenson Button has written off Fernando Alonso's title credentials despite the Ferrari star's shock Malaysian Grand Prix victory.

A week after his near-perfect triumph in Australia to kickstart the new Formula One season in stunning fashion, Button was left apologising to McLaren following yesterday's race at Sepang.

"Even after such a bad race - and that's hopefully my bad race for the year gone - I'm still only 10 points off the lead, and that's Alonso in a Ferrari. That's not the worry," Button said.

"I'm also only five points behind Lewis, who is the guy in a competitive car, so still not bad considering the day I had.

"Lewis is definitely my main rival, and you have to say the Red Bulls as well.

"Those are the guys I still think are the main ones at this point in the season, and will be for quite a few races.

"The Mercedes' show signs of speed in qualifying, and we'll have to see what they can do in a nice dry race, and see where we stand compared to them.

"But the team we should still be worried about the most are Red Bull."

Even though Alonso himself insisted his victory meant nothing had changed within Ferrari given the overall uncompetitive nature of their car, McLaren team principal Martin Whitmarsh is refusing to write them off.

"You can never underestimate Ferrari, but it was a turn-up for the books they were able to win," said Whitmarsh.

Asked if he was worried they would emerge in Barcelona with a decent car, with the Spanish Grand Prix pinpointed as the race when teams deliver a major upgrade, Whitmarsh replied: "You always are.

"When you are trying to win a world championship you are always worried that at every race weekend you go to someone will deliver a bit more performance.

"If you're honest about it, at the back of your mind, you are wondering whether anyone turns up with a eureka moment and they overhaul you.

"But it's a long, long championship ahead, and although we're not in bad shape, nothing is taken for granted here.

"No one, with confidence, can predict the outcome of this year's world championship, and that's how it should be."

There was a degree of concern, though, that after starting one-two on the grid, McLaren again failed to maximise their chance.

A one-three in Australia was reasonable, but collecting 15 points in Malaysia from Lewis Hamilton's third - due to being held up by Ferrari's double-shuffle first pit-stop when they brought in both drivers one after the other - was barely acceptable.

"It was one of those days when it doesn't always go well for you," said Whitmarsh.

"I don't think we got anything dramatically wrong, but we had those two decisive moments that ensured the race was not what we wanted it to be.

"In the dry, if nothing had gone wrong then I think we had the pace to be one-two, and we should have been.

"But given the conditions it could have been a lot worse, yet we are second and third in the drivers' standings and leading the constructors' after two races.

"We've a reasonably quick car, and hopefully we've some decent performance upgrades coming for China to get this championship rolling again for us. We've a great season ahead of us."