Naomi Osaka's return, Andy Murray's tough loss highlight Day 1 of US Open

Updated Aug. 31, 2021 12:04 a.m. ET

Few tennis tournaments are bigger than the US Open, and if Monday was any indication, it's going to be a wild ride to the finish line.

The 2021 US Open kicked off with a bang, including a great comeback by Coco Gauff and a return to action by Naomi Osaka. 

But it all started with an epic clash between 2012 champion Andy Murray and Stefanos Tsitsipas, the No. 3 seed in the tournament.

Murray surprisingly won the first set 6-3 to set the stage for a potential upset. But it was only the beginning of a testy five-set clash between the two.

The opening set was the first Murray had won against a top-five player since 2017, but Tsitsipas would ultimately come back to win – though not without controversy.

The match lasted just short of five hours, the length due in part to an extensive bathroom break and medical timeout that Tsitsipas took during the match. This brought the ire of Murray after the match.

Nevertheless, Tsitsipas avoided the upset and Murray was eliminated, and that wasn't the only nail-biter of the day.

American teenage phenom and No. 21 seed Gauff had to hold off Magda Linette of Poland. 

Gauff found herself behind immediately, losing the first set 7-5 to Linette before winning the next two 6-3, 6-4 to advance to the second round.

She battled back in front of Brooklyn Nets head coach and Hall of Famer Steve Nash.

This all set the table for the return of Osaka, the defending U.S Open champion.

And she did not disappoint, defeating Marie Bouzková in dominant fashion (6-4, 6-1) to advance to the second round.

Osaka had recently missed some major events, pulling out of the French Open after the first round and skipping Wimbledon altogether for mental health reasons, citing anxiety and concerns with the media. She did compete in the Tokyo Olympics in her native Japan.

Osaka even offered insight into a change in psyche on the eve of the US Open in a statement posted to her Twitter account.

The win over Bouzková also was a reminder of Osaka's dominance on hardcourt, extending her winning streak on the surface and placing her in the company of some of the greatest tennis players ever.

Afterward, Osaka had a sweet moment in which she gave a bit of swag from the Olympics to a young fan.

Now she continues on her journey to defend her title.