Juan Martin del Potro reached the French Open third round on Thursday after Spanish opponent Nicolas Almagro quit in tears during the third set with a left knee injury.

In a moving conclusion to the match, Del Potro sat next to the stricken, sobbing Almagro on Court Two, offering him water while patting the head of the inconsolable 31-year-old.

The giant Argentine had also gone to the Spaniard’s aid when he had collapsed at the back of the court, weeping, just moments earlier.

Del Potro had taken the first set of the second round clash 6-3 before Almagro claimed the next by the same score.

They were locked at 1-1 in the third when Almagro quit.

Del Potro, playing Paris for the first time in five years after battling a series of wrist injuries, also suffered an injury scare himself when he pulled up, holding his left leg in the second set.

The former US Open champion goes on to face either world No 1 Andy Murray or Martin Klizan for a place in the last-16.

Del Potro reached the quarter-finals on his last appearance in 2012 with a best run to the semi-finals three years earlier.

Almagro, a former world No 9, is now ranked 69th.

He arrived in Paris having been forced to retire with a knee injury against Rafael Nadal in Rome.