When David Weir suffered two punctures in last year's Virgin London Marathon men's wheelchair race it not only put an end to his formidable lead, but dashed his dreams of winning a fifth London title.

Weir finished third in 2010 in 1:37:01 but is back this time determined to end a losing streak that goes back to 2008. "I've been coming second or third too much at London," said the 31-year-old Londoner today. "I want that fifth win but I have to take it every race at a time."

He will be full of confidence on Sunday though, having won the New York Marathon last November for the first time and taken three gold medals at the IPC World Championships in New Zealand this January at the 800m, 1500m and 5000m.

Weir did not take part in the marathon there on safety grounds, so London title is his main goal for this year.

"I had a shoulder injury before the Worlds which set me back a bit," he said. "It was doubtful whether I would even compete in New Zealand, but the New York win spurred me on."

Weir, who is to become a father for the second time in August, is taking nothing for granted on Sunday, and was quick to praise his rivals. "Heinz (Frei) is pushing really well, plus Marcel (Hug), while Josh (Cassidy) and Saul (Mendoza) are also on top form, so it could be anybody's win," he said.

Cassidy, the Canadian who won last year, was second to Weir in the 2010 Great North Run, and relishes the London atmosphere. The 26-year-old has been training with 2009 London winner Kurt Fearnley in the build-up. The Australian has chosen to compete in Boston this year, and without Fearnley the competition could be even more open.

"Training with Kurt has been helpful," said Cassidy. "I am physically stronger than last year, and although I am in good shape, I just don't know what shape the others are in."

Frei, the Swiss world record holder, has won London three times in the 1990s and comes fresh from a Paris win in a respectable 1:29:12. For an athlete who concentrates on handcycling these days, the 53-year-old Frei is still expected to pull out a good performance on the road.

Mendoza has not won London since 2005, but is still respected at 44. The Mexican retired formally from athletics after the 2008 Paralympics, so competing on the road is more for pleasure these days.

Frenchman Denis Lemeunier's last London win was in 2001 but he is remembered for his sprint finish against Weir and Fearnley in 2008. He set his best on this course in 2009 when he clocked 1:32:40, but after not finishing the race last year, he will be eager to make his mark amongst the top finishers.

"It all depends on the wind in London," said Cassidy. "If the weather's right, records could happen."

In the women's race, Shelly Woods is looking to break her bad luck. The 24-year-old won here in 2007, and has the second best marathon time on paper, but she has been bugged with punctures in the last two years.

"The weather plays a major part in the race. If it's wet the debris comes to the surface and you're more likely to get problems," she said.

Woods won a 5000m bronze at the Worlds this January, but the Blackpool athlete did not show her usual form. "I had a pretty disappointing Worlds but my preparation for this has gone well so you never know. The crowds are great here and they make the race a lot easier," said the British record holder.

She faces one of the best line ups in London. Past winners Amanda McGrory (2009) and Sandra Graf (2008) both could feature. McGrory is looking forward to competing particularly after winning the Paris marathon last Sunday.

"It's always a good confidence booster coming from your last win. I'm hoping it shows this weekend," said the 24-year-old American.

Graf, from Switzerland, broke the course record in 2008 when she won in 1:48:04. She's finished second in the past two years, but was ranked number one in 2010.

There'll be much interest in McGrory's college team mate, the London debutante Tatyana McFadden. McFadden is still new on the marathon circuit, having only ever completed four full marathons.

As a sprinter, she never understood the fascination in long distance. But once she had adapted, her performances have been amongst the best - she won Chicago in 2009 and the New York Marathon in 2010.

"I'm still pretty excited about racing marathons," said the American. "I have a lot to learn in sprinting so I am sure I have a ton of work to do over longer distances.

"The marathon brings the competitor out in everyone and maybe that's why I have set the goal of winning New York, Boston and London by the time I am 22."

Whoever claims the victories on Sunday, it is likely to be a memorable race for both men and women wheelchair athletes.