The 24-year-old smashed the 10,000 and 5000m world records last year and is entered for both events in Tokyo.

"It would be a mountain to climb, but the challenge is up to me," said Cheptegei, who is competing in his second Olympics following his sixth-placed finish in Rio five years ago. "If I win gold in the 10,000m I would still be grateful."

Cheptegei broke Kenenisa Bekele's 15-year-old 10,000m record in Valencia with a time of 26:11.00, trimming more than six seconds off the Ethiopian's mark.

The 2019 world champion has a good chance to add an Olympic title to his name, as defending champion Mo Farah, winner of the 5000m and 10,000m double at the 2012 and 2016 Olympics, failed to qualify for his third Games.

Another medal contender, Kenya's Geoffrey Kamworor, the 2015 world silver medallist, was forced to pull out of the Olympics last week due to a foot injury.

But the road to victory will not be easy for Cheptegei and a stiff challenge could come from his compatriot Jacob Kiplimo.

The youngest Olympian in Uganda's history when he ran the 5000m heats in Rio as a 15-year-old, Kiplimo has proved his pedigree this year with a world-leading performance in Ostrava of 26:33.93, the seventh fastest ever recorded.

Other medal contenders include Ethiopian Yomif Kejelcha, 23, who finished second to Cheptegei at the 2019 world championships.

While Kenya's chances for medals at the distance diminished with Kamworor's withdrawal, the man who replaced him, Rhonex Kipruto, is another contender for a podium finish in Tokyo.

The only Australian in the men's 10,000m field is Patrick Tiernan.

Stewart McSweyn also qualified for the 10,000m and 5000m but has chosen to focus solely on the 1500m where he has the best chance of a podium finish.

The men's 10,000m is the only medal event on day one of the track and field program.

Australian Associated Press