Japanese short track speed skater Kei Saito has been suspended from the Winter Olympics after a positive doping test.
Saito had been due to compete Wednesday in the second heat of the Men's 5,000 Meter Relay, according to the official Games website.
Instead, the 21-year-old athlete will leave the Olympic Village Tuesday.
This is the first doping violation of the 2018 Pyeongchang Games. However, CAS pointed out that no results from the Games have been affected by the violation.
The Japanese Olympic Committee said it will hold a press conference later Tuesday.
The build up to the 2018 Winter Olympics had been dominated by doping news, with Russia banned from taking part after the International Olympic Committee (IOC) found the country had engaged in "systemic manipulation" of anti-doping rules.
Russian athletes who could prove they were clean were "invited" to compete as Olympic Athletes from Russia (OAR). They wear a uniform with that name on it, and the Olympic anthem is played at medal ceremonies for Russian athletes.
Some 150 athletes were cleared to compete, dozens more had appealed to CAS in the hopes it would force the IOC to reverse their bans, but their hopes were dashed last week when the court ruled against them, hours before the Games officially kicked off.
One of the athletes' whose Olympic dream was ended Friday was another speed skater: Viktor Ahn, a highly decorated athlete who was born in South Korea and competed for the country before becoming a naturalized Russian citizen.