Usain Bolt expressed his unhappiness for returning one of his nine gold medals due to a doping case involving teammate Nesta Carter.

"I wasn't pleased -- nobody would be pleased over the years to lose a medal," Bolt said Friday. "It's just one of those things -- things happen. I'm not happy about it but what can I say?"

The IOC said Wednesday that Carter tested positive for methylhexaneamine, a banned stimulant, in reanalysis of samples from the 2008 Beijing Olympics.

"I haven't seen Nesta now but I hope he's not blaming himself too much about this,Bolt said of his teammate. "It's just one of those things that happen in life I guess. So I just wait and see what happens."

Carter and Bolt were teammates on the winning 4x100-meter relay team, which also included Michael Frater and Asafa Powell.

Asked if he thinks it would affect his legacy, Bolt said: "Personally I don't think it should. I've worked hard over the years. I've shown my dominance throughout the years. I think by losing one medal that shouldn't be a problem, you understand, because I've done individual events and I've won all three (gold medals) at three Olympics."

Jamaican sprinter Usain Bolt has returned one of his nine Olympic gold medals in a doping case involving teammate Nesta Carter. Alexander Hassenstein/Getty Images

The relay title in Beijing completed the first of Bolt's three gold-medal sweeps in the 100, 200 and relay at three straight Olympics.

Trinidad and Tobago is in line to get the gold medal from 2008, Japan could be upgraded to silver, and fourth-place finisher Brazil could get the bronze medal.

Carter testified by videoconference to an IOC disciplinary hearing held in Lausanne on Oct. 17.

The IOC's ruling states that Carter noted he was taking supplements in 2008 "advised in this respect by his coach, Mr. Stephen Francis."

"The athlete explained that he had given several samples for doping controls whilst he was taking Cell Tech and Nitro Tech before the 2008 Olympic Games and he had never tested positive for a prohibited substance," the detailed verdict stated.

"He therefore did not believe that these supplements could contain prohibited substances. He did not understand how methylhexaneamine could have been found in 2016."

Though methylhexaneamine was not specifically named on the 2008 list of prohibited substances, it "fell within the scope of the general prohibition of stimulants having a similar chemical structure or similar biological effect as the listed stimulants," the three-member IOC panel wrote.

Carter can appeal the sanction to the Court of Arbitration for Sport. However, the IOC panel already anticipated one challenge in its written verdict.

"The Court of Arbitration for Sport has confirmed that the presence or use of substances falling within the scope of generic definitions of the prohibited list, can be used as a basis of establishing anti-doping rules violations," the verdict said.

The Associated Press contributed to this report.