Canadian newcomer Josh Cassidy celebrated his first marathon title when he won the Virgin London Wheelchair Marathon this morning. After months of training and competing against the world's greatest, his victory points to a successful road racing future.

All talk in the build-up had been about Australian Kurt Fearnley and Briton David Weir. But Cassidy's tactical performance was enough to secure their victory and prize money of $15,000.

The drizzly weather at the start hinted towards a slow race with the athletes more wary of wet conditions. Cassidy chose slower tyres than Weir, who used a new Draft racing chair built for endurance. The 25-year-old Canadian said: "The weather played a part today. I haven't trained in rain for three months so I didn't expect the result today, but it means so much to me".

For the last few weeks, Cassidy, a graphic designer, has been training with Weir in London. Weir rated him as a rival, saying he was in good form, but at 5km the British racer was leading the pack of seven men. Fearnley, the reigning champion, was already 22 seconds behind. At 10km, Weir and the Japanese, Kota Hokinoue, moved ahead slightly, with Fearnley lagging three minutes behind the pack.

By Tower Bridge Weir had a comfortable lead with Cassidy a minute behind. The Briton has four London titles on his belt and now looked odds on to claim a fifth.

But it all changed when he reached the Embankment, with the finish line virtually in sight. Weir had suffered a puncture to his front tyre at 15 miles, so when he got another on his back wheel at 20 miles, he knew the title was over. Cassidy passed Weir and went on to claim victory in 1:35:21.

Switzerland's Marcel Hug took second in 1:36:06 on his first London Marathon. The 24-year-old, who has won the Padua Marathon in the past, much prefers track to road. He said: "I am very pleased to come second with such quality people around me. But that's the end of road racing for me now. I'm going back to the track!"

Weir battled through the punctures and crossed the line in a respectable, yet unfortunate, third in 1:37:01.

He said: "I tried my hardest but it was like doing another 20 miles on top when I got two punctures. As soon as your back tyres go, it's a struggle to go very far. I was in great shape this year and felt back to normal after my illness, but it's obviously disappointing."

Cassidy was elated with his biggest win so far on the marathon circuit. He said: "I knew it was going to be a tough race as I've been with some of these guys before but I was really excited about competing in London for the first time.

"There are lots of great races in this country and London is definitely one of them."

Hokinoue was fourth in 1:40:59 while the course record holder, Fearnley, came fifth in 1:41:37. Nine-times Boston winner, Ernst Van Dyk of South Africa, finished sixth in 1:44:11.