Former US Open champion Juan Martin del Potro said on Saturday his comeback next week after two and a half years of injury is "more a farewell than a return" to tennis.
Del Potro is set to announce his retirement after he plays at the Argentina Open in Buenos Aires, his first tournament since fracturing his kneecap in June 2019 at Queen's in London.
The former world No 3 has undergone four surgeries on his knee for that injury while slipping to 757 in the world rankings.
The 33-year-old Del Potro, who beat Roger Federer in the 2009 US Open final, said his knee troubles had him "living a nightmare".
"It's more a farewell than a return. I've tried different treatments and seen doctors for many years, and I never imagined retiring from tennis without playing," he said at a press conference.
"I couldn't find a better tournament than Buenos Aires to be able to do it. After this week, I'll think about the future."
The injury-prone Argentine also broke his knee at the Shanghai Masters in October 2018 and before that suffered multiple wrist injuries that also required four surgeries.
Del Potro won the last of his 22 tour titles at the Indian Wells Masters in 2018.
He took silver and bronze at the Olympics and helped his country win the Davis Cup in 2016.
Del Potro last played the Argentina Open as a 17-year-old in 2006, losing in the first round to former world No 1 Juan Carlos Ferrero.