Motocross rider Antonio Cairoli will end his career after the season, he announced at a press conference in Rome.
The 35-year-old Italian has been Jeffrey Herlings' biggest competitor in MXGP in recent years.
"This is not an easy decision. I've always said that numbers and statistics didn't mean much to me," said Cairoli, who became world champion no fewer than nine times.
"I think it was an achievement for me and my family to win one world championship, so it's very special to have had such a career."
"I feel this is the right time to stop," said the KTM motocross rider.
"There is still a lot more to do in life after 2021, but for now our goal is very clear."
In his eighteen-year career, Cairoli, who will remain with KTM as ambassador after this year, has already won 93 GPs and has been on the podium 177 times.
The last world title of the Italian veteran dates back to 2017. A year later Herlings took the title and the last two years the main prize went to the Slovenian Tim Gajser.
Honda driver Gajser is also at the top of the standings this year, but with nine GPs to go, Herlings and Cairoli still have a chance at first place.
Standings in MXGP
1. Tim Gajser (Slo) - 355 points
2. Romain Febvre (Fra) - 327 points
3. Antonio Cairoli (Ita) - 326 points
4. Jeffrey Herlings (Ned) - 321 points
5. Jorge Prado (Spa) - 315 points