Kiptum and Hassan triumph in astounding London Marathon
The 23-year-old Kiptum broke the course record with an astonishing time of 2 hours, 1 minute and 25 seconds.
Having broken clear of the field, Kiptum - who became the third fastest male marathon runner of all time on his debut in Valencia in December - faded towards the finish and missed out on Eliud Kipchoge's world record by 18 seconds.
Geoffrey Kamworor made it a Kenyan one-two, finishing second in 2:04:23, with Ethiopia's Tamirat Tola third in 2:04:59.
British distance great Mo Farah, in his last marathon before retirement, finished ninth in 2:10:28.
Hassan recovery
Earlier, it looked as if Hassan's debut marathon would end in disappointment.
The 5,000 and 10,000 metres Olympic gold medallist from the Covid-delayed 2020 Tokyo Games had been in the leading group but was dropped and holding her side after the hour mark.
It would have been impressive enough had the Ethiopian-born Dutch runner, a Muslim who had been fasting due to Ramadan, just completed the course on the rainswept streets of the British capital, with Hassan then grabbing her hip and stopping to stretch off the injury.
Hassan, however, recovered to rejoin the leaders with three miles to go.
Despite making a mess of collecting a drink from a water station, the 30-year-old recovered and even offered rival Yalemzerf Yehualaw, last year's winner, a swig from her bottle.
Hassan, 30, then burst clear in a sprint finish to win in a time of 2 hours, 18 minutes and 33 seconds.
Kenya's Alemu Megertu was second in 2:18:37, with compatriot Peres Jepchirchir, the Olympic champion, third in 2:18:38.
This was the first time Jepchirchir had been defeated in a major marathon race.
"It was just amazing. I never thought I would finish a marathon and here I am winning it!" Hassan told the BBC.
Hassan added: "I had a problem with my hip, which made me stop. But it started to feel a little bit better.
"And then I missed one of the drinks stations! I didn't practice that part of the race because I have been fasting and so that was quite difficult. But I needed it!
"At 20km I knew that I could kick on because I didn't feel that tired and I didn't care how I finished, I just wanted to get there.
"I wasn't thinking about winning or how fast I was going to be and I think that was a good thing for me today."
Marcel Hug won a fifth men's wheelchair race in London, just six days after winning the Boston Marathon, with the Swiss star shattering his own course record in a time of 1hr 23min 43sec.
Australia's Madison de Rozario, the 2018 champion, won the women's wheelchair race when she edged out four-time champion Manuela Schar in a sprint finish.
