British driver Jenson Button ended a three-year wait for pole position by finishing fastest in Belgian Grand Prix qualifying, while defending champion Sebastian Vettel will start today's race from 11th place.

Button, who won the season's opening GP in Australia, overcame earlier balance problems to grab his first pole of the season yesterday, the eighth of his career and his first ever in his 50th race for McLaren.

The 32-year-old Button seemed to be struggling earlier in the day with the understeering of his car, but got it right when it mattered with a best lap of 1 minute, 47.573 seconds.

Button, vying for his 14th GP win, is seventh in the championship and 88 points behind overall leader Fernando Alonso of Spain.

It has been one of the most unpredictable seasons for years, and that trend looks set to continue in Spa with unheralded drivers Kamui Kobayashi of Japan starting second and Pastor Maldonado of Venezuela in third place.

Kobayashi is only the second Japanese driver to start on the front row after Takuma Sato in 2004 at the Nurburgring.

Maldonado, competing in only his second F1 season, has a good chance to secure his second victory of the season after winning the Spanish GP in May. He showed the potential of the Williams car, and was quickest in the first qualifying session.

Vettel's bid to catch Alonso looks to have taken another blow, while his Red Bull teammate Mark Webber will start the race with a five-place grid penalty, knocking him down from seventh to 12th, with McLaren's Lewis Hamilton moving up from eighth to seventh.

Alonso was sixth in qualifying behind Sergio Perez in fifth and fourth-place Kimi Raikkonen .

Alonso posted the fastest time in yesterday's third practice, where drivers frantically fine-tuned their cars for qualifying.

Button had complained to his McLaren team that "we've got to look at the balance," while Mercedes driver Nico Rosberg pulled out after five laps, and his day got worse as he incurred a five-place grid penalty for a gearbox change.