That extended his winning streak in Doha. He had won the 1500m race at the World Championships in Doha in 2019 and was the reigning world champion.
But then he finished 4th in the Kenyan Olympic trials, behind younger rivals, and looked off-form.
It was clear Timothy Cheruiyot wasn't at his best at the Kenyan Olympic trials as he limped off the track, after a disappointing finish. Only after the Kenyan team for the Tokyo Olympics was announced, was it clear that he had more than just a hamstring issue at the trials.
Apparently he had also lost a relative at the time of the trials, which must have been on his mind as he raced.
At the time, he hadn't known that he'd be selected for the Kenyan team eventually, and returned to the Diamond League in Monaco on 9 July 2021. He had set his previous personal best at Monaco in August 2020.
He didn't disappoint in 2021 either, beating Mohamed Katir (who also set his personal best in the race) and Jakob Ingebrigtsen to win convincingly.
Coincidentally, Timothy Cheruiyot also beat Jakob at Monaco in 2020.
His time of 3:28.28 minutes for 1500m at the Monaco Diamond League race in 2021 was not only his personal best but also the world leading time in 2021.
Timothy Cheruiyot's triumph was soon followed by the Kenyan team announcement, prompted by an anti-doping technicality. One of the athletes, Kamar Etyang, who finished ahead of Timothy Cheruiyot at the Kenyan Olympic Trials, was ruled ineligible to represent Kenya at the Tokyo Olympics.
Kamar is all of 18 years and hence perhaps not very active on the international running circuit, which means he didn't get tested often enough.
Timothy Cheruiyot is likely to put his change in Olympic hopes to good use as he heads to Tokyo. His compatriots on the Kenyan 1500m team, Charles Simotwo and Abel Kipsang, are also making their Olympic debuts.
However, his rivals for the gold medal are likely to be the Ethiopians led by Samuel Tefera and Teddese Lemi as well as a familiar one - Jakob Ingebrigtsen.
Timothy Cheruiyot leads the main contenders for the gold medal at the Tokyo Olympics
Timothy Cheruiyot was sitting at the top of the World Athletics rankings for 1500m for 2021 even before his 2021 Monaco Diamond League performance. Jakob is predictably 2nd in the same ranking, given his terrific form in 2021. However, not all of those in the top 10 in that list are currently in great form, except Timothy Cheruiyot and Jakob Ingebrigtsen.
By the same token, some outside the top 10, like Mohamed Katir of Spain, have shown remarkable form in 2021. Timothy Cheruiyot has beaten each of his main rivals - Tefera, Ingebrigtsen and Katir at Monaco and before. Elijah Manangoi, who has beaten Timothy Cheruiyot more than once, including at the 2017 World Athletics Championships, isn't going to be at the Tokyo Olympics.
Manangoi is currently under a two year ban for whereabouts failures under anti-doping regulations.
Timothy Cheruiyot's fresh personal best while running against some of his competitors for the gold at the Tokyo Olympics should give him confidence as he heads to Tokyo.
Timothy Cheruiyot has great racing credentials with triumphs at the 2019 World Athletics Championships and multiple Diamond League wins between 2016-2021.
Timothy Cheruiyot has also shown amazing consistency across different racing conditions, ranging from relatively pleasant European weather to the challenging circumstances in Doha. That should serve him well in Tokyo, which is likely to be much warmer than the typical Diamond League race weather.
If Timothy Cheruiyot medals at the 1500m at the Tokyo Olympics, it will be a welcome development in Kenyan athletics. Kenya hasn't won an Olympic medal in the men's 1500m since Asbel Kiprop won gold at the 2008 Beijing Olympics. Asbel Kiprop is also serving a doping-related ban.
That's quite surprising given the dominance of the Kenyans over other international events including the World Athletics Championships. Timothy Cheruiyot's success would also help improve the clean credentials of Kenyan athletes, given the unpleasant developments in the careers of both Kiprop and Manangoi.
Timothy Cheruiyot would also be looking to secure his place in athletic history at the Tokyo Olympics and beyond. He's currently 7th on the all-time list for 1500m timings. Six of the seven have Olympic medals (Kenyan Silas Kiplagat is the exception).
There are four athletes of Kenyan origin (Bernard Lagat is now a US citizen) on that list and three have Olympic medals.
Given his recent form and the fact that he's still 25 years old, Timothy Cheruiyot should improve his all-time ranking. Timothy Cheruiyot could well be the next 1500m legend and an Olympic medallist at the Tokyo Olympics.
Also read Jakob Ingebrigtsen - Norway's medal hope