Tyler Clary apologised to US swimming team-mate Michael Phelps after accusing the 14-time Olympic champion of being lazy.
Phelps was upset after the attack by 23-year-old Clary in a Californian newspaper.
Clary trained with the 27-year-old at the University of Michigan for a year and claimed: “Basically, he was a swimmer who didn’t want to be there.
“They can talk about all these goals and plans and preparation. I saw it. I know it. It’s different. And I saw somebody who has basically been asking to get beat for the longest time.”
The outburst has raised tensions at the University of Tennessee in Knoxville, where Phelps and Clary are preparing for the Olympics alongside the rest of their team.
Clary — who is taking part in his first Games — went on Twitter to say he was honoured to compete alongside “the best swimmer in history” and concluded: “I’m sorry @MichaelPhelps.”
Clary’s coach, Jon Urbanchek, said he was “very shocked” by the remarks but that the swimmer had told him “everything was taken out of context.” Urbanchek, who is also close to Phelps, added: “I hope they will sit down and talk about it. I know Michael is a little bit upset.”
Phelps will compete in seven events in London while Clary will race in the 200metre backstroke and 200m butterfly.
