Buenos Aires,  Playing for the first time since March 2019, the injury-hit Argentine Juan Martin del Potro lost 6-1, 6-3 to countryman Federico Delbonis in the first round of the Argentina Open.

Following four right-knee surgeries, the former world No. 3 admitted he might have played his last match.

However his name is enlisted in the draw of this month's ATP 500 Rio Open. Last week, the former US Open champion (2009) hinted that his appearances in Buenos Aires and Rio Open may mark his final ATP Tour tournaments.

"I will speak to doctors again. I have to take care of my knee and then we will see. I will always leave the window open. (But) if today was the last time I will leave happy," he said after the match.

"It's difficult to explain how I felt on the court. So many emotions. The atmosphere was crazy, the people were crazy, and I had one of my best ever matches in my career with the crowd," he added.

After leaving the court, he had this message for fans hoping to see him play again, "I don't know if it's going to happen, because the pain in my knee is very high. But I will keep doing a big effort to fix the knee, and if I get that, maybe I will have another chance to play."

The world No. 42 Delbonis will meet Spaniard Pablo Andujar in the next round on Thursday.