The US Open has been rocked by a first round upset, with Novak Djokovic stumbling in five sets to little-known Argentinian Mariano Navone.
Djokovic went up two sets to one having dropped the first in a tie-breaker, but then the 38-year-old's fitness let him down, with one of the all-time greats dropping the final two sets 6-2, 6-1.
The Serbian struggled with fitness around his back and his health during what could be Djokovic's last time at Flushing Meadows before retirement.
The 24-time grand slam champion has never been knocked out in the first round at the US Open, and it's something that has only happened twice in his career, at the Australian Open back in 2005 and 2006.
His worst performances prior to this at the US Open were in the same years, 2005 and 2006, when he was ousted in the third round of each tournament.
Since then, he has made the semi-finals on 14 occassions, winning the tournament four times and playing in another six finals.
Djokovic became emotional as the fifth set slipped away from him, with the Serbian potentially set to hang up the tennis racquet after the more-than-four-and-a-half-hour match on centre court in New York.
The star veteran came into the tournament as the fourth seed, and it will now pave the way for either Italian Matteo Berrettini or Swiss legend Stan Wawrinka to play Navone in the second round.
While the tournament also opens up for the likes of Carlos Alcaraz, who is the second seed, and potentially others on that side of the draw including local favourites Frances Tiafoe and Ben Shelton.
Elsewhere on Day 1 of the final grand slam of the year, things went almost as expected on the men's side of the draw, although British 29th seed Cameron Norrie was knocked out in a four-set match.
In the women's singles, Australian Taylah Preston managed to pick up an upset win in straight sets over American Alycia Parks, but no other seeds were bundled out of the tournament as the hot weather hit Flushing Meadows.
