Madison de Rozario has sped to glory at the London Marathon, winning the women's wheelchair race in a course record from a world-class field after an exhilarating sprint finish.

Australia's double Paralympic champion, honoured as the nation's top woman athlete in 2022, prevailed in one of the closest-fought races in the race's history, pipping her Swiss pursuer Manuela Schar by just one second.

De Rozario got into pole position as four of the world's best jockeyed for position coming into the final sprint down the Mall, and held off her chasers with a long, powerful push to the line to win her second London crown, five years after her first.

She clocked a new course record of one hour 38 minutes 51 seconds, just one second clear of Schar, with another Swiss Catherine Debrunner and American Susannah Scaroni just behind. Only six seconds separated the quartet.

It was just another honour to add to the 29-year-old de Rozario's remarkable CV, following her two Paralympic wins in Tokyo, three world titles and four Commonwealth golds.

"That was an intimidating field to be a part of. You look around and see these three women you're pushing with and thinking 'these are the best athletes in the world'," smiled the Perth athlete.

"Cat (Debrunner) won this race last year in a course record, Manuela's been dominant for such a long time and Susannah's come off the back of winning Boston by five minutes.

"So to win a sprint from them was amazing."

Even more remarkably, de Rozario was able to produce her brilliant sprint finish just six days after finishing runner-up in the Boston Marathon, when she finished more than five minutes adrift of Scaroni as runner-up.

For a moment in the denouement, it appeared as if four-time winner Schar was going to squeeze by, but de Rozario wouldn't relinquish her slight advantage.

"I saw Manuela's wheel coming up alongside me, but I just kept focused. The race is so important to me - and to be alongside people I admire so much is amazing."

The Australian also reckoned it was a particularly sweet victory after having to withdraw before the start with illness on the day of last year's London race.

"When I had to pull out last year, it was devastating for me," said de Rozario. "So, just to cross the finish line was really special."

In the men's elite race, won by Kenya's Kelvin Kiptum, who sped off alone for the final miles to smash Eliud Kipchoge's 2019 course record in 2:01:25, Australia's lone elite competitor, Brett Robinson, came home a creditable seventh in 2:10:19.

The 31-year-old national record holder from Canberra even finished two places ahead of Sir Mo Farah (2:10:28) in the English great's final marathon.

In the best women's field ever assembled, flying Dutchwoman Sifan Hassan sprinted to victory on her debut in 2:18:33, while Australia's leading finisher was Ellie Pashley, 13th in 2:29:37.