Jenson Button admits that he remains confused by McLaren's sudden fall from grace at the Bahrain Grand Prix, acknowledging that it wasn't due to gains made by its rivals.

The Briton, who is missing this week's three-day test at Mugello, would only have finished fifth at best at Sakhir, but was forced to retire in the closing laps after an exhaust problem affected his MP4-27. With team-mate Lewis Hamilton finishing only eighth after a couple of problematic pit-stops, the stage was left clear for Red Bull and Lotus to steal the spotlight just a week after the Woking team had made them look ordinary in China.

The slip allowed reigning champion Sebastian Vettel to reclaim top spot in the championship standings from both McLaren drivers, but that isn't what vexes Button the most.

"There would have been [positives] if we had finished," he told, "If I hadn't have had the problem at the end, then I'd be leading the championship. But, even if I had finished, there would still have been a negative because we weren't quick.

"Our race pace is normally very good, but it wasn't in this one; the pit stops weren't that special either, and our tyre deg (degradation) was higher than most, so all in all a very difficult day. We just didn't have anything."

Although he finished outside the points in Malaysia after colliding with Narain Karthikeyan's HRT in tricky conditions, Button was more concerned that Bahrain may indicate a longer-term problem that could see McLaren's apparent early season advantage eroded by its rivals.

"In the race, we were in a different category compared to Lotus and Red Bull," he sighed, "Compared to the four guys in front, they were a second quicker than us, and they haven't put a second on the car in the last two or three races. Something is working for them, and something isn't working for us, and I don't really understand.

"We were racing the Ferraris and, for most races this year, they have been a second slower than us. It's difficult to understand what the problem is."

While hoping that the Mugello test will help unearth the lack of pace, Button was also quick to acknowledge that mistakes being made throughout the team were also hampering his chances of heading the points table.

"It's tough, [but] I know we have to limit our mistakes because we have had too many," he conceded, "We have to improve. I think we're quick, but we have to make the consistency better."

"Every race you want to have a good result and you know that a no-score is massive and it really hurts," he had earlier conceded to Britain's Sun newspaper, "You've got to be consistently near the front. I don't think it means you hold back going out for a win. You're not going to hold back if there is a manoeuvre or a move to go for, but consistency is going to be very important this year. In your heart, we're all here to do one thing and that's to be the first to cross the finishing line, but if that's not possible you're there to pick up points."