Queens, New York - The 2021 US Open is underway and some notable American tennis players got the action started their runs for tennis’ last grand slam title of the year.

Two American tennis stars started off the day’s action in the women’s draw on Monday afternoon. Sloane Stephens (28), the 2017 US Open champion, started her quest for another tournament title against her best friend, the 2017 runner-up, Madison Keys.

Heading into the match, both Stephens and Keys were thought to be the American women most likely to go far into the tournament, since Venus and Serena Williams recently withdrew due to injury concerns.

Stephens needed a third-set tiebreaker to eventually win 6-3, 1-6, 7-6(7) and advance to the next round.

She moves on to face fellow American and 21st seed Coco Gauff, who also needed three sets to outlast her opponent, Poland’s Magda Linette 5-7, 6-3, 6-4.

Gauff is among the youngest players in the tournament but will have to play like a true veteran if she wants to take out the former Open champ on Wednesday.

Superstar Naomi Osaka returned to tennis on Monday night after getting herself prepared for the last tennis major of 2021. She last played a couple of weeks ago in the Western & Southern Open in Cincinnati, Ohio, falling to Jil Teichmann in the third round.

The US Open has been very kind to Osaka, who won the event twice so far.

The third-ranked 23-year-old was on her game on Monday, taking care of the Czech Republic’s Marie Bouzkova 6-4, 6-1 in just over 90 minutes of match time.

Up next, Osaka will face Serbia’s Olga Danilovic in the second round on Wednesday.