Jenson Button admitted he was surprised to secure pole for the Spanish Grand Prix at Catalunya after dramatically stealing top spot on the grid in the dying seconds of the qualifying session.

The Brawn GP man looked like playing second fiddle to team-mate Rubens Barrichello after the Brazilian set a stunning pace in the second session of qualifying - with Barrichello then setting provisional pole in the final stages of Q3.

The former Ferrari man was denied a long overdue return to pole position when Sebastian Vettel moved to the head of the field with a lap of 1min 20.660secs but as Red Bull started to celebrate, Button produced a stunning lap of 1min 20.527secs to steal pole with the final lap of the session.

However, it wasn't just the quick lap itself that had proved to be impressive, with Button having been forced to push on his out-lap to get one final flying lap in - crossing the line just two seconds before the chequered flag flew to set what would turn out to be the pole position time.

"That could have gone very, very wrong!" he admitted afterwards. "We timed it quite well I thought, but then I had Kubica, who I thought was on an out-lap, but I had to let him through when he caught me up.

"The team then told me I had four seconds - four seconds slower than a proper timed lap - to get through sector three. I got over the line with a few seconds to spare but it was more luck that judgement on getting out at the end.

"It's been the best lap I've had all weekend. I struggled to hang on to Sebastian on the low fuel runs, but I got the quickest lap on high fuel. This was a surprise in a way and when the team came on the radio to say I had pole, it felt good."