Jenson Button was quick to play down his speed during testing at Jerez having emerged on top of the pile in the first day of running in Spain.

Button bounced back from a fuel pump issue on Tuesday morning to be quickest as the eleven F1 teams all hit the track for the first pre-season test of the year, with the McLaren man comfortably clear of the chasing pack.

However, the 2009 champion insisted that his lap-time wasn't the important thing to take away from his first run behind the wheel of the MP4-28 and it was his feeling in the car that was the big positive to take away from the day.

"Who knows what that really means?" he was quoted by the official F1 website in reference to his time. "Lap times are really not the important thing right now. So forget about the lap time.

"I don't know if it is quick or not as you never know what people do and it's only the first day of testing - there is nothing that frightens me, so it's definitely a good starting point. When I drove out of the garage I immediately felt comfortable in the car - very much at home with the way it feels. But I have to repeat myself: it is the first day of testing and you are not going to know if it is a championship-winning car or not."

The Briton did however admit that losing time on track on the first day of running hadn't been ideal.

"That is not what you really want - only three laps into the day and having an issue," he said. "But that is how things go sometimes. It took us quite a long time to fix the fuel pump issue - we definitely didn't expect that to happen. But once we sorted it out I was able to do some good laps and it was a nice feeling.

"Doing 36 laps is not what we came here for on the first day, but things like that do happen. I was surprised that we had an issue but, as I just said, once we fixed that it was a smooth ride. It was very close to what I've experienced in the simulator and that is good news and very important for future developments. Let's hope that this fuel pump issue was our only issue of this test and we can now go out and build on reliability."

Button will be back in the car on Thursday with Sergio Perez on track today [Wednesday].