SPA-FRANCORCHAMPS (AFP) - Defending drivers world champion German Sebastian Vettel defied his doubters on Saturday when he powered his Red Bull to pole position for Sunday's Belgian Grand Prix. In capricious conditions at the sprawling and spectacular Spa-Francorchamps circuit in the Belgian Ardennes, the 24-year-old leader of this year's title race demonstrated no lack of pace or form as he outpaced nearest rival Lewis Hamilton in the closing second of a dramatic qualifying session. Briton Hamilton, the 2008 champion, suffered damage to his McLaren car when he was smashed into deliberately by Venezuelan Pastor Maldonado's Williams at the end of Q2 after Michael Schumacher, the seven-time champion, was eliminated in the opening seconds of Q1 when he suffered a mechanical failure on his Mercedes. For the 42-year-old German, it was a setback in his bid to celebrate the 20th anniversary of his F1 debut with a flourish in Sunday's 44-laps race. Hamilton, with the side-pod of his car held by heavy black tape, wound up second by four-tenths of a second, but a full second clear of third-placed Australian Mark Webber in the second Red Bull. For Webber, it was an anti-climax on his 35th birthday after topping the times in final practice in the morning when it was confirmed he will stay with Red Bull in 2012. Brazilian Felipe Massa was fourth for Ferrari ahead of German Nico Rosberg of Mercedes, Spaniard Jaime Alguersuari of Toro Rosso and, remarkably, Brazilian Bruno Senna, on his debut with the Renault team after an acrimonious promotion in place of German Nick Heidfeld. Two times champion Fernando Alonso of Ferrari was eighth ahead of Mexican Sergio Perez of Sauber and Russian Vitaly Petrov in the second Renault. Vettel's pole was his ninth this year and the 24th of his career and brought him his best starting position to date in Belgium. "Oh yes, oh yes" he screamed on his slowing down lap. "That's the answer. Thank-you..." On a cold day with intermittent rain showers and temperatures hovering around 13 degrees Celsius, the qualifying hour began in a brief window of dry conditions. There was immediate and unexpected drama when Schumacher lost his rear right wheel, and control of his Mercedes car as he descended the hill at the top of the circuit. To the dismay of his many fellow-German fans in the crowd, the 42-year-old seven times champion slid across the track and off into a gravel trap as the errant wheel rolled alongside his car. "I don't know what happened - something unexpected happened," said the veteran who will start from the back of the grid. Almost predictably, rain began to fall as Q1 drew to a close with Jenson Button on top of the times ahead of Webber and Hamilton while six other drivers were condemned to drop out along with Schumacher. The second mini-session, Q2, began after another cloudburst had eased off, but it had hardly started when it was red-flagged and stopped after German Adrian Sutil lost control of his Force India on the climb out of Eau Rouge and hit the barriers. This left Alonso down in 11th when, with rain falling and only six minutes remaining, the session resumed. Luckily, for Alonso, conditions improved, he found some grip and after going fastest - and airing his frustrations - fell out of the top ten before bouncing back quickest again. That relief for Ferrari was in contrast to the disappointment at McLaren, where McLaren's Button missed the cut and qualified 13th, having apparently yielded briefly to Hamilton, who was second fastest, in the final minutes when drier conditions prevailed. "It was a misunderstanding," said a glum Button. In a bizarre incident in the final seconds, Maldonado swerved across the circuit at the exit of La Source hairpin and crashed into Hamilton's McLaren. That was done deliberately," said Hamilton. "He just straight across me..." It was an unsavoury example of appalling behaviour by the Latin American and a serious sanction from the stewards, including Briton Nigel Mansell, was expected as the leaders began lapping, on slicks, in the top-ten shootout.