Paula Radcliffe hit a new high in a magnificent year yesterday as she shattered the world record marathon time in Chicago.

The 28-year-old Briton's awesome strength and speed saw her cross the finishing line in two hours 17 minutes 18 seconds - slicing a stunning 89 seconds off the world record time set by defending champion Catherine Ndereba in this event last year.

Marathon novice Radcliffe made no secret of the fact she wanted to smash Ndereba's time, despite insisting victory at the stamina-sapping distance was more important than her winning time.

Radcliffe's debut over 26 miles 385 yards saw her emerge victorious in April's Flora London Marathon with a world record for a women's-only race of 2:18:56.

Yesterday she thrived in the environment of running alongside talented male opponents.

Radcliffe prepared perfectly for the race at her altitude training base of Font Romeau high in the French Pyrenees.

She never faltered and went from strength to strength as huge crowds cheered her along her momentous path to the greatest victory of her career, ahead of Ndereba (2:19:26) and Japanese hopeful Yoko Shibui (2:21:22).

Radcliffe did not look back at her rivals during the first ten miles, before making a strong surge just before the halfway point.

The tempo increase quickly carried her through 13.1 miles in 69:05 and, more importantly, enabled her to open up a 15-yard lead over Ndereba.

There was no surrender from ''Catherine the Great,'' but the 29-year-old defending champion struggled to keep up with the Bedford star.

Although Radcliffe's head bobbed in traditional manner, her blonde hair was not visible until she discarded her blue bobble hat after 16 miles.

The gap at 20 miles was 24 seconds, and despite feeling pain two miles later her body responded instantly to her new demands. The question was not whether Radcliffe would break the world record but rather how big the margin would be.

The reward saw her become the first woman to break two hours 18 minutes, and also the first British woman to hold the world record since Dale Greig held the honour after her win on the Isle of Wight in 1964.

Radcliffe quickly recovered from her exploits and said: ''I held back in the first half and then in the second half I pushed on a little bit. I was running with some US guys a lot of the time and they were really helping me.

''There was also a lot of support out there for me. I thought it would be really quiet after London, but it wasn't at all. I was amazed how many British people were out there.''

The win capped a year of success which has seen Radcliffe retain her World Cross Country title and land the Commonwealth 5000m and 10,000m gold medals, as well as her marathon success in London.

But Radcliffe admitted yesterday's win - which earned her £160,000 - topped them all.

She added: I've got the world record so it's got to rank at the top. Ever since London I have been working towards this and my track races went 100 per cent to plan.

''Then we went away and put in a lot of hard work and I'm just happy it's all paid off.''

''Now I'm just going to have a holiday - I'm putting my trainers away until I get back home.''

In the men's event, Khalid Khannouchi was not far away from the world record time he set in London in April.

Khannouchi was initially happy to follow South African Gert Thys, who towed the field through the half distance in 62:30.

The solid pacemaking suggested the 2:05:38 mark belonging to the Moroccan-born world record holder - granted US citizenship two years ago - would be broken.

But Khannouchi delayed making his effort for victory until the start of the 24th mile, steaming past Japan's Toshinari Takaoka to cross the line and win the race for a fourth time.

His winning time of 2:05:56 put him 20 seconds clear of Takaoka, who reduced his personal best by three minutes.

Third-placed Kenyan Daniel Njenga also ran the best race of his career, finishing almost five minutes faster than he had ever done before to be given the same time as Takaoka in a blanket finish.

Khannouchi set a world record time of 2:05.42 here three years ago and said afterwards: ''When you come here you have to compete against the best. So it was something special to win again.

''It was very important to know the course.

"I was emotional after hearing my name shouted thousands of times from the crowd.'