CHICAGO (REUTERS/AFP/NYTIMES) - Kenyan Brigid Kosgei broke Paula Radcliffe's 16-year-old women's marathon world record but former Alberto Salazar-coached athletes, including Mo Farah, were never a factor in the Chicago Marathon on Sunday (Oct 13).

The 25-year-old Kosgei set a blistering pace from the start to run 2hr 14min 4sec and shatter Radcliffe's previous record of 2:15:25 which the Briton had set in London in April 2003.

Her record came a day after Kenyan Eliud Kipchoge became the first man to run a marathon in under two hours but the mark, in Vienna, will not count for record purposes as it was on a specially prepared course in a Vienna park.

While the International Association of Athletics Federations recognises the 2:17:01 clocked by Mary Jepkosgei Keitany at the 2017 London Marathon as a "women-only" world record posted without male pace setters, it is Radcliffe's mark - so long untouchable - that has been the grail for female marathon runners.

"They (spectators) were cheering, cheering and I got more energy to keep faster," said Kosgei, the defending Chicago champion who also won this year's London Marathon.

"I kept saying, 'Tomorrow is my day,'" she added. "I wanted to be the second Kipchoge - the Kipchoge for women. I focused on that."

"I was not expecting this," Kosgei said of the world record. "I was expecting to run 2:16 or 2:17. It's amazing to run 2:14, but the world record was in my head. When I started the race, I was thinking I need 2:15 for Paula's record."

She had signalled her intentions with an astonishing first 5km in 15:28 - so far inside Radcliffe's world record pace that it seemed she might have ruined her chances out of the gate. But she settled into a more sustainable rhythm, and powered relentlessly to the finish line. Her halfway split of 1:06:59 had her comfortably inside world record pace, and her lead expanded over the second half as her pursuers felt the effects. The pacers dropped away in the closing kilometres, leaving Kosgei to break the tape alone, her arms raised in celebration.

Radcliffe witnessed the fall of her record.

"We always knew the time would come when the record would be broken," said the Briton. "When I saw how fast Brigid was running in the first half of the race, I knew she had a good chance of getting the record.

"I've always said 17 is my lucky number and it was exactly 17 years ago to the day that I set my first world record here in Chicago."

Ethiopians Ababel Yeshaneh and Gelete Burka finished more than six minutes behind Kosgei.

Kenyan Lawrence Cherono sprinted past Ethiopian Dejene Debela to win the men's race in 2:05:45 but British defending champion Farah placed eighth in 2:09.58 and previous winner Galen Rupp failed to finish.

The time was Farah's slowest in a marathon by more than a minute. He was not available for comment.

Farah and Rupp are under the spotlight as both were formerly coached by the now-banned Salazar as was American Jordan Hasay, one of the women's favourites who also did not finish.

Rupp suffered a calf strain at about 9.5km into the 42.195km race and he was forced to drop out near the 37km mark, his management company said in a statement.

Hasay felt a sharp pain in her hamstring after 3.2km, stretched and tried to continue, but was unable to, the statement added.

The race was the first for the three since Salazar was banned from the sport for four years by the United States Anti-Doping Agency (Usada) for "orchestrating and facilitating prohibited doping conduct".

Salazar has said he plans to appeal against the ruling.

Debela was a second behind Cherono and fellow Ethiopian Asefa Mengstu took third place in 2:05:48.

"Towards the end I felt like I could kick forwards, I still had enough energy to sprint and it's amazing," Cherono said. "I am so happy. It's my second major marathon and to come only a few months after Boston is brilliant."

American Daniel Romanchuk overwhelmed the men's wheelchair field to defend his title in an unofficial 1:30:26. The 21-year-old finished more than three minutes ahead of British runner-up David Weir.

Swiss Manuela Schar also retained her title, the 34-year-old winning the women's wheelchair race in an unofficial 1:41:08. Former champion Tatyana McFadden took second in 1:45:22.