Two-time Olympic marathon champion Eliud Kipchoge was hoping for a dream finale to his career at the age of 39 but ended up handing over his running shoes to a fan.

The only man to run under two hours -- albeit in an unofficial race -- the Kenyan superstar decided enough was enough in Paris and stopped running around the 30-kilometre mark.

In scenes captured by an AFP reporter in the crowd, Kipchoge turned to fans and handed over his shoes, bib and socks to supporters, receiving a rapturous reception.

He then climbed wearily into a waiting van and was driven away as the crowd cheered wildly.

Kipchoge was aiming to win a historic third straight gold but was about eight minutes off the pace when he decided to throw in the towel.

Ethiopia's Tamirat Tola won the race in an Olympic record time of 2hr 06min 26sec, declaring it to be the "greatest day" of his life.

For Kipchoge though, it was "a tough day at the office".

"This is my worst marathon. I have never done a DNF (did not finish). That's life," he said.

He said he experienced pain in his back after the 20-kilometre mark.

Kipchoge was non-committal on his future.

"I don't know what my future will hold. I will think about it over the next three months. I still want to try to run some marathons," he said.