Rafael Nadal admitted to being "under stress" after wasting numerous opportunities against Leonardo Mayer, but the world number one was pleased with his response.
The Spaniard squandered his first 13 break-point chances before settling to claim a 6-7 (3-7) 6-3 6-1 6-4 victory over Mayer in the third round at Flushing Meadows on Saturday.
Nadal, who faces Alexandr Dolgopolov in the last 16, said letting so many chances slip against the Argentinian made him nervous.
"You are under stress when you see that you have opportunities almost in every game, and you are not able to convert it," the 15-time grand slam champion told a news conference.
"Yeah, of course, when finally I did it, everything changed. I was able to play more freely, to start to attack better with my forehand. I changed more forehands down the line, hitting some good backhands later.
"I think the level of tennis after that break was very positive. I hope that last three sets can be a good turning point for me because, in my opinion, I played much better than the two previous days later in the match. You need matches like this.
"Now I have the opportunity to compete again, to try to do it well. I am in the second week. That's the important thing. I've already won three matches in a row. That's important news for me.
"I know I have a tough opponent [Dolgopolov] out there now, tricky one, because he's going to play aggressive, he's very tough, he has a lot of talent, and he's playing well. He won easily today. Against [Tomas] Berdych he played well, too. It's going to be a tough one. So for me it's another opportunity to compete, try to compete better than what I did."
Once Nadal finally broke in the seventh game of the second set against Mayer, the two-time winner in New York took complete control.
The 31-year-old said he was happy with his performance later in the match, a good sign after he was also tested by Taro Daniel in the second round.
"I overcame a tough situation. That's very positive for me. I am very happy about this," Nadal said. "I know I cannot play very well always, and not the whole match.
"But for me the most important thing is I give my best and I played with the right intensity and all the time with the motivation to win the match, even when things were not going very well.
"For me, that's all the things I can ask of myself. Playing better, playing worse, that's something sometimes I cannot control. But the level is there because I have been practicing very well. And later in the match I have been playing well."