Seeking that elusive first Grand Slam title, Murray began his U.S. Open campaign Monday with a straight-set victory over Alex Bogomolov Jr. that included some hairy moments. The Olympic gold medallist overcame early breaks in the first two sets of a 6-2, 6-4, 6-1 win.
The third-seeded Murray won the final five games of the first set and the last four games of the second after falling behind early against the 73rd-ranked Bogomolov.
Murray, who won the gold medal in his home country at the London Games, also reached the final at Wimbledon.
Back at the site of her greatest victory, Samantha Stosur looked like a champion again, not the player who has often struggled this year.
The Australian began the defence of her Open title with a dominant win, needing 51 minutes to beat 64th-ranked Petra Martic 6-1, 6-1 in the tournament's first match at Arthur Ashe Stadium before rain suspended play for more than two hours.
"As soon as I got here, it was just a good feeling and excitement to be back to a city that obviously brought me so much last year," Stosur said.
The last time Stosur played on this court, she stunned Serena Williams in the 2011 final at Flushing Meadows for her first Grand Slam title. But in so many ways, that 6-2, 6-3 victory was starting to feel as if it happened much more than a year ago.
Stosur lost in the first round in front of the home fans at the 2012 Australian Open. She lost in the second round at Wimbledon, then again in the first round at the London Olympics.
Sandwiched in between, she made a run to the semifinals of the French Open, but fell apart by committing 21 unforced errors in the third set of her loss to Sara Errani.
"Today kind of carried on from exactly how I was feeling last year," Stosur said. "Hopefully that's a good omen. ... Last year I did feel that comfort out there and nothing bothered me; today was along the same lines."
Against Martic, who withdrew from the Olympics with a left foot injury, Stosur won the first 19 points, five away from a golden set, before the streak ended on a double-fault.
"It pops into your head and you think, 'Oh, that would be cool,'" Stosur said of winning a set without dropping a point.
She was still nearly perfect, with 22 winners and 10 aces. She didn't face any break points.
Ninth-seeded Li Na reached the second round for the first time since 2009, beating Britain's Heather Watson 6-2, 6-3. She's coming off a victory in Cincinnati, her first title since the 2011 French Open.
Li was a top-10 seed when she lost in the first round at Flushing Meadows in each of the previous two years.
Marion Bartoli of France, seeded 11th, defeated American Jamie Hampton 6-3, 7-6 (5), and 19th-seeded Nadia Petrova of Russia advanced with a 6-3, 7-6 (3) win over Jarmila Gajdosova of Australia.
It was a rough first day for the German women, with 16th-seeded Sabine Lisicki and 18th-seeded Julia Goerges both losing.
The American men got off to a good start with wins by two wild cards, 32-year-old James Blake and 19-year-old Jack Sock.
Sock took a two-set lead over Florian Mayer before the No. 22 seed quit after feeling faint and dizzy. Sock won the U.S. Open boys championship in 2010, becoming the first American to take that title since Andy Roddick, 10 years earlier. He came into this year's tournament ranked 248th and without a win over a top-50 player.
Sock was ahead 6-3, 6-2, 3-2 when Mayer retired.
Blake reached the second round of a Grand Slam event for the first time this year, beating Lukas Lacko 7-5, 6-2, 3-6, 6-3. He had needed a wild card to make his 12th appearance at the Open after his ranking fell out of the top 100. He hadn't lost in the first round at Flushing Meadows since his debut in 1999.
Blake, who has twice made the quarterfinals at the Open, won the first two sets against the 54th-ranked Lacko before the rain delay.
Top-seeded Roger Federer plays American Donald Young in the night session Monday.
Also playing in Arthur Ashe Stadium are No. 3 Maria Sharapova, against Melinda Czink of Hungary, and No. 23 Kim Clijsters, opening the final tournament of her career with a first-round match against American Victoria Duval. Clijsters missed last year with an injury, but has won the tournament the past three times she's entered — in 2005, 2009 and 2010.
AP National Writer Eddie Pells contributed to this report.
Follow Rachel Cohen at https://twitter.com/rachelcohenap .