Juan Martin del Potro has admitted that persistent wrist problems almost forced him to retire from tennis.

The Argentine won the US Open in 2009, but since then his career has stalled as a result of three separate operations on the affected joint.

He recently returned to action at Indians Wells, but Del Potro has conceded that he was previously "close" to calling time on his career.

"I'm so happy to be on tour again after almost two years without tennis life," he told the ATP's official website.

"It was frustrating for me at the beginning of my injuries. But I kept working hard, trying to fix the problem every time.

"I was close to quitting tennis. I got frustrated at home and I didn't watch tennis on TV because it was sad for me. It was close. But now, I have many good things to take from the tour. I would like to play tennis and that's it."

The 27-year-old is currently ranked 366 in the world, having previously been as high as number four.