American artistic swimmer Anita Alvarez was rescued from the bottom of the pool by her coach after collapsing at the World Aquatics Championships.
The 25-year-old was not breathing and sank after completing her routine in the solo free final in Budapest.
Her trainer, Andrea Fuentes, pulled Alvarez to the surface before she was taken away on a stretcher.
The US swim team later released a statement from Fuentes saying that Alvarez “feels fine now”.
Alvarez previously collapsed after a routine during the Olympic qualifiers in Barcelona last year, with Fuentes also rescuing her on that occasion.
Of the most recent incident, Fuentes said: “Anita is fine – the doctors have checked all her vitals and everything is normal – [her] heart rate, oxygen, sugar levels, blood pressure etc. Everything is good.
“We sometimes forget that this happens in other high-endurance sports. [such as] marathon, cycling, cross country. We’ve all seen images where some athletes don’t make it to the finish line and others help them get there.
“Our sport is no different from others, just in a pool, we push the limits and sometimes we meet them.
“Anita feels fine now and the doctors also say she is fine. Tomorrow she will rest all day and will decide with the doctor whether or not she can swim in the free team final.”
Spanish newspaper Marca reported that Fuentes, a four-time Olympic medalist, said he had come in “because the lifeguards weren’t doing it.”
Speaking to Spanish radio, she said: “It felt like a whole hour. I said things weren’t right, I was yelling at the lifeguards to get in the water, but they didn’t understand what I said or I don’t understand.
“She wasn’t breathing. I went as fast as I could, like it was an Olympic final.”
Alvarez scored 87.6333 points for his routine, finishing seventh in the finals.