Juan Martin del Potro was reduced to tears in what he expects to be his final tennis match as the former US Open champion bowed out of the Argentina Open.

The 33-year-old Argentinian lost 6-1 6-3 to fellow Argentinian Federico Delbonis in Buenos Aires, having come back from four rounds of knee surgery to get back on court.

He saved seven of 12 break points in a determined effort against Delbonis, but Del Potro, who had been on the injured list since June 2019, was in no shape to compete for victory over his compatriot.

One of the most popular players on the tour, who might have achieved many more great things had wrist and knee trouble not played him over the last decade, Del Potro bid an emotional farewell.

The moment got to Del Potro as he prepared to serve at 5-3 down in the second set. His emotions spilled out, with a towel failing to mask his tears as a passionate crowd rallied behind him, chanting: "Ole, ole, ole, ole, Delpo, Delpo."

A fan carried a flag bearing the message: "The Tower of Tandil keeps fighting. Thank you." Tandil is Del Potro's home city.

After the match, Del Potro said: "The truth is that this is a moment I never wanted to come. Health leads me to have to make a decision: I made too much effort in these two and a half years.

"Sometimes I can lose. I do not have the strength that everyone believes. I think I fulfilled all the dreams in tennis and the most difficult thing to achieve, which is the affection of the people.

"I feel like I've given it all. This is a day I never wanted to come, but I'm going to remember it for the rest of my life."

He was relieved to be leaving on his own terms, saying: "Now I am calm because my last match was possibly on the court and not in a press conference. I will always remember this."

Del Potro, whose US Open triumph came when he beat Roger Federer in a sensational 2009 final, has accepted a wildcard to the upcoming Rio Open, but he signalled he is unlikely to now take that up.

"Yes, I was planning to go to Rio," he said, quoted by La Nacion. "But... I think I already gave everything until the last point."

Del Potro was an Olympic silver medallist in 2016, beaten in the Rio final by Andy Murray, and later in the same year he helped Argentina win the Davis Cup.

It was fitting that Delbonis, who won the decisive rubber against Croatia after Del Potro was victorious in both his singles matches, was the man on the other side of the net on Tuesday. He and Del Potro shared a long, affectionate hug at the net at the end of the match.

Del Potro's mother, Patricia, was among those in the crowd. The ATP said it was the first time she had attended one of his matches. She was pictured embracing her son off court after the match ended.

Other matches happened in Buenos Aires on Tuesday too, a highlight being Brazilian Thiago Monteiro's 6-3 6-3 win over seventh seed Albert Ramos-Vinolas.

At the Dallas Open, first-round winners included Jack Sock, Jordan Thompson and Liam Broady.