Defending champion Andy Murray struggled with his serve and spent plenty of time scampering after shots, but responded to the challenge by raising his game Friday to reach the third round of the US Open.
British third seed Murray, the reigning Wimbledon and Olympic champion, advanced with a 7-5, 6-1, 3-6, 6-1 victory over Argentina's 81st-ranked Leonardo Mayer in a match of rivals who were both born on May 15, 1987.
"Very tough match," Murray said. "Both of us ran a lot and it was very humid. I'm just glad I was able to put it together and pull it out in the fourth set."
In the grander scheme, looking at how he will need to play to capture his third career Grand Slam title, Murray felt the match was a positive step.
"I finished the match well. I played well when I needed to. That's a good sign," he said. "I want to keep improving as the tournament goes on. You don't want to play your best right at the beginning, so I hope I can get better."
Murray connected on only 57 percent of his first serves but was broken only once in the match, yet that was primarily because of his ability to chase down balls from the South American shotmaker.
"I was a bit frustrated at points in the match because I was doing quite a lot of the running for a lot of it," Murray said. "I wasn't getting much depth on my returns, so when he was serving I was having to do a lot of running.
"I served pretty well in my first match and then today struggled to control the first serve. You don't feel like you're dictating the match. It can be frustrating."
Murray, who improved to 39-7 on the season, won his second Grand Slam title in July at Wimbledon and also owns crowns this year from Brisbane, Miami and Queen's. Murray will claim his 29th career title if he defends the Open title.
Adding to the issues Murray faced was the venue, secondary Louis Armstrong Stadium rather than the main Arthur Ashe Stadium court, and the timing of the match, which began in daylight and finished after sunset.
"I've had some tough matches there in the past and today was the same," Murray said. "It's a court I haven't played my best tennis on, that's for sure. And for me I think the conditions, well, it's day and night. It's completely different."
The 26-year-old Scotsman became the first British man to win a Grand Slam since Fred Perry in 1936 with his triumph over Novak Djokovic in last year's US Open final. He has now reached the third round in 22 Grand Slams in a row.
Next up will be Germany's Florian Mayer, who advanced by defeating US qualifier Donald Young 7-5, 6-3, 6-4.
"He has caused a lot of guys problems over his career," Murray said. "I'll need to play well to beat him."
Murray broke Mayer at love in the 12th game to capture the first set, then broke again in the second and sixth games to claim the second as well.
Mayer, who fell to 0-12 against top-10 foes, swiped Murray's first service game in the third set and held the rest of the way to force a fourth set.
The match turned when Mayer sent a backhand long to give Murray a break and a 3-1 lead. Murray broke again for a 5-1 edge and held serve to end matters after two hours and 41 minutes.
"He definitely started the match very well. Then towards the end of the first set, a few errors started to come. When I got up an early break in the second, I think he started maybe going for too much," Murray said.
"He was still going for big shots at the beginning of the third set, but he started making them for a while. Made it very tough."