The 2020 U.S. Open looks a lot different this year, with no fans, a stark contrast to the some-50,000 cheering spectators who typically follow the tennis in person. 

Play continued with Day 2 of the 14-day tournament on Tuesday, and there were a handful of matches that garnered the excitement that began when play opened Monday, with Novak Djokovic defeating Damir Dzumhur in three sets and Naomi Osaka defeating Misaki Doi, also in three sets. 

On Tuesday, Andy Murray beat Yoshihito Nishioka and Serena Williams won against Kristie Ahn.

Murray is ranked No. 134 in the world, but the 2012 U.S. Open champion is making a welcome return after missing the last four Grand Slam events while recovering from hip surgery.

Meanwhile, Williams was as clinical as ever in her two-set victory over Ahn. 

There were plenty of other exciting matches on Tuesday, and the full results can be viewed on the U.S. Open website. But we'll break down some of the top matches below as well as scores and notable stats. 

Top Men's Results

No. 2 Dominic Thiem def. Jaume Munar (retired) 

No. 10 Andrey Rublev def. Jeremy Chardy, 6-4, 6-4, 6-3

No. 11 Karen Khachanov def. Jannik Sinner, 3-6, 6-7, 6-2, 6-0, 7-6

No. 15. Felix Auger Aliassime def. Thiago Monteiro, 6-3, 6-7, 7-6, 7-6

Andy Murray def. Yoshihito Nishioka, 4-6, 4-6, 7-6, 7-6, 6-4

After nearly two hours of play, Jaume Munar retired, sending Dominic Thiem to the second round. Munar injured his knee in the second game of the second set and required a medical timeout, after which the Spaniard pulled out of the match. 

Thiem, who has advanced three Grand Slam finals, has yet to win a title. He came into U.S. Open play as the No. 2 seed with Rafael Nadal and Roger Federer out, but his play hasn't yet matched his high seeding. 

Rafael, last year's U.S. Open men's singles champion, opted out of this year's tournament over COVID-19 concerns. And Federer announced he would abstain from all championship play until 2021 because of setbacks in his recovery from knee surgery in February. 

Two years ago, Jeremy Chardy ended Andrey Rublev's U.S. Open tournament in the first round. On Tuesday, Rublev finally got to return the favor. It marked his eighth win in 12 matches at the U.S. Open and his first since the ATP Tour resumed. 

It took five sets, but Karen Khachanov finally pulled out the win over Jannik Sinner. Early on, Sinner was going for the upset and up two sets, before he began slowing down and needed a trainer. 

Sinner put up a hard-fought battle, however, and the 19-year-old, who was the youngest player in the ATP's top 100 at the beginning of the year, will surely have many more U.S. Open opportunities in his future. 

There was a five-set battle going down on another court as Murray staged a furious comeback to triumph over Nishioka. The win was a triumph for the former world No. 1, who sat outside the top 100 following his absence; put another way, it was his first Grand Slam singles action in 596 days. 

It was just another impressive comeback win in a string of them throughout Murray's career. 

Now we'll see if Murray can recover before his second-round match against Canada's Felix Auger Aliassime, who defeated Thiago Monteiro in four sets Tuesday. 

Top Women's Results

No. 3 Serena Williams def. Kristie Ahn, 7-5, 6-3

No. 9 Johanna Konta def. Heather Watson, 7-6, 6-1

No. 10 Garbine Muguruza def. Nao Hibino, 6-4, 6-4

No. 22 Amanda Anisimova def. Viktoriya Tomova, 7-5, 7-5

Ysaline Bonaventure def. No. 25 Shuai Zhang, 4-6, 6-3, 6-2

Though their match began later in the day than expected, it didn't take long for Serena Williams to defeat Ahn in two sets. 

In doing so, the 23-time Grand Slam champion set a record: 102 wins at the U.S. Open, breaking a tie with Chris Evert. 

Williams advanced to face Margarita Gasparyan in the second round, against whom she has a 2-0 head-to-head record. 

It was the Battle of the Britons on Court 5, as Johanna Konta took on Heather Watson. Konta had never before lost to her compatriot in three previous matches. With the win, Konta preserved her perfect record not only against Watson, but also against all fellow Brits.

Konta relied on her serving to see her through, with 11 aces and 27 winners to 19 unforced errors while winning 80 percent of her first serve points.

In the first match of Tuesday, Nao Hibino got off to a hot start against Garbine Muguruza, whose ankle has plagued her this year, causing her to pull out of the Western & Southern Open. But the Spaniard returned to form and took the match in two sets. 

On the women's side, Amanda Anisimova is the teen to watch. The 19-year-old is the highest-ranked teenager in the 2020 draw and showed why on Tuesday, defeating Viktoriya Tomova in two sets while hitting 40 winners.  

Shaking things up on Tuesday, Ysaline Bonaventure pulled off the shocking upset over No. 25 Shuai Zhang. Though clinical in her play, Zhang has never progressed past the third round of the U.S. Open. This year, she didn't make it out of the first.