Juan Martin del Potro’s return to the US Open final is a celebration of friendship that saw the 2009 champion through his darkest days of injury and doubt.

A dozen friends from del Potro’s hometown of Tandil have gained fame in Flushing Meadows, their serenade of “Ole, ole, ole — Del-Po, Del-Po” an infectious accompaniment to his every match.

Despite Del Potro’s affectionate post-match teasing, they’re more than a boozy bunch of boyhood friends.

They’re the people who helped him through when it seemed recurring wrist injuries would end his career.

The nadir came in 2015, when multiple surgeries had failed to produce a solution.

“They are very important for me to be in this stage at the moment because they were behind me in that year, trying to keep my mind positive to never give up during my wrist problems,” said Del Potro after reaching the final when defending champion

Rafael Nadal retired injured after dropping the first two sets.

“I didn’t know if I will be a tennis player again or not. But I’m here. I’m excited to keep surprising the tennis world, as I did with myself.” Del Potro looked headed for stardom when he beat Rafael Nadal and Roger Federer in succession to win the 2009 US Open.

Instead years in the wilderness followed.

But Del Potro, resurgent this season with his first ATP Masters 1000 title in Indian Wells and a title in Acapulco, is on the threshold of another Grand Slam triumph.

“I cannot believe that I will have a chance to play another Grand Slam final here, which is my favorite tournament,” Del Potro said.

His resurgence hasn’t been just a matter of getting healthy. His wrist injuries required him to make changes to his game, adding a slice backhand option to his armoury.

“I mix it up a lot, my backhands with the slices, drop shots (because of) my wrist problems. But it’s working good,” he said.

He knows he’ll need every weapon at his disposal in Sunday’s final against Novak Djkovic, who claimed his 13th Grand Slam title at Wimbledon.

Djokovic has won 14 of their 18 career meetings, including in the quarter-finals of the 2012 US Open.

American John Isner, beaten by Del Potro in the quarter-finals, said the Argentine is playing “some of the best tennis ever right now for him”.

And Del Potro, who’ll turn 30 on September 23, is relishing every minute of it as the memory of his “worst moment” recedes.

“Now I’m having a good present, looking forward for the future. I didn’t expect to get these kind of emotions playing tennis again. Reaching finals, winning titles, having my highest ranking ever — everything is almost perfect.”