Kenyan marathon runner Samuel Kalalei has been banned from athletics for four years after testing positive for banned blood-boosting hormone EPO.
The 23-year-old tested positive at the Rotterdam Marathon in April where he set a personal best to finish seventh.
Kalalei, who won the Athens Marathon in 2017, was provisionally suspended from the sport in June.
He is the third Kenyan athlete to receive a doping ban this year while four further cases are still pending.
They include former Olympic 1500m gold medallist and three-time world champion Asbel Kiprop, who was found to have traces of EPO after a test in November 2017.
In the same month, Rio 2016 Olympic women's marathon gold medallist Jemima Sumgong received a four-year ban.
In September, the World Anti-Doping Agency (Wada) said Kenya had a "serious problem" with doping.