Stoner excels in the Donington rain

(CNN) -- Defending world champion Casey Stoner of Australia defied appalling conditions to claim pole position for Sunday's British round of the MotoGP world championships at Donington Park.

The Ducati rider negotiated heavy rain to set a lap of one minute 38.232 seconds to finish fully 0.649 seconds ahead of championship leader Valentino Rossi of Italy on a Yamaha.

Chris Vermeulen of Australia finished third fastest at 0.786 seconds, but it was a story of Stoner domination as he bids to overhaul Rossi in the championship standings where he trails by 50 points.

Stoner was claiming the 12th pole of his career and his second of the season after starting from first place at the Catalunya Grand Prix.

The American pair of 2006 world champion Nicky Hayden and Colin Edwards qualified fourth and fifth fastest.

There was disappointment for home rider James Toseland who came off three times in the treacherous conditions on Saturday, watched by a massive crowd with over 80,000 expected on race day.

"It's obviously hugely disappointing to have my worst qualifying session of the season at my home Grand Prix," Yamaha rider Toseland told the Press Association.

In the 250cc class, Aprilia rider Alvaro Bautista of Spain edged Marco Simoncelli of Italy to take pole position, with Hector Barbera of Spain third.

Simone Corsi of Italy took pole in the 125cc class on his Aprilia, 0.129 seconds ahead of world champion Gabor Talmacsi of Hungary. Sergio Gadea of Spain took third.