US Open 2016: Dominic Thiem retires hurt to send Juan Martin del Potro through

Austrian Thiem, ranked 10th in the world, was a set and a break down on the Arthur Ashe court at Flushing Meadows when he withdrew from the match with a right knee injury.

Progression to the quarter-finals looked unlikely for the perennially injured Del Potro when he himself received treatment on a shoulder problem just three games into the match and with his opponent already a break up.

But the trainer worked magic on that troublesome shoulder, and the big Argentine stormed back into the match with five straight games to take the first set 6-3.

Del Porto carried that form into the second set and – injury permitting – looked likely to have too much for Thiem. But the Austrian’s knee gave way before he even had a chance to respond, sending Del Potro through to the last eight after getting the short match that his weary body clearly needed.

Thiem's withdrawal prompted further questions over the wisdom of his hectic touring schedule.