Jamaica's Olympic champion Usain Bolt said the possibility of losing a gold medal is "heartbreaking".
Bolt's 4x100m relay team-mate Nesta Carter is reported to have tested positive for a banned substance during retesting of 454 samples from the 2008 Beijing Olympics.
The result of a 'B' Sample follow-up test is not yet known.
"I'm not too pleased about the situation," said reigning World and Olympic sprint champion Bolt, 29.
Bolt was speaking after he recorded the second-fastest 100m time of the year, winning in 9.88 seconds in Jamaica.
"For years you've worked hard to accumulate gold medals and you work hard to be a champion, so it's heartbreaking, but it's one of those things," Bolt told RJR communications in Kingston.
"If I have to give back my gold medal, I'll have to give it back."
Carter has yet to comment on the case.
He ran Jamaica's first leg in Beijing, followed by Michael Frater, Asafa Powell and Bolt, as they recorded a then-world record time of 37.10 seconds.