Novak Djokovic collapses to ground after brutal rally with Daniil Medvedev in US Open final

Novak Djokovic appeared to be suffering physical issues during the gruelling second set with Daniil Medvedev in the US Open final.
Following one particularly gruelling point at 3-3 in that second set, Djokovic collapsed in a heap on the court.
He was lying on his back looking up at the roof of Arthur Ashe Stadium and was seemingly struggling to catch his breath.
Martina Navratilova, who is commentating for Sky Sports, said: "Another monster rally from Medvedev. Djokovic just collapses."
Earlier in that same game, the 36-year-old bizarrely stumbled forward after missing a shot.
Djokovic seemed to be struggling throughout the second set and was holding on at points against his Russian opponent.
Medvedev had set points to draw level with the 23-time Grand Slam winner, but failed to convert.
The Serbian superstar eventually claimed that set in a tiebreak after more than 100 minutes of exhausting tennis.
Djokovic went on to close out the match in the next set, winning 6-3 7-6 6-3.
It was his 24th Grand Slam title, a fourth in New York, and saw him equal Margaret Court's all-time record.
The stars were out in force at Flushing Meadow to see him make history, with Hollywood actor Matthew McConaughey even sitting in his box.