-- NEW YORK -- Sam Stosur was "nervous as anything" sitting outside the women's dressing room before the 2010 French Open finals when her coached spotted Rafael Nadal walking by and jokingly asked, "Rafa, do you have any tips for nerves?"
Nadal, who had already won four French titles and the next day would begin a run of five more in a row, did not have advice. He did, however, make a telling comment Stosur still remembers.
"He said, 'No, but when you work it out, tell me,' " Stosur recalled. "It affects everyone."
Perhaps no one has struggled more conspicuously this week and this year than Serena Williams, who has had several bouts with nerves on court as she attempts to complete the first calendar-year Grand Slam in women's tennis in 27 years.
"I've been completely relaxed, chill ... and I'll be fine again," Williams insisted after admitting to feeling stressed in a second-round match in which she committed four double-faults in one key game late in the first set and 10 in the match against a 100th-ranked qualifier.
From golfers who miss tap-in putts, to baseball players who suddenly develop the yips and can't get the ball to the next base, to tennis players who lose the feel for a stroke they have been hitting all their lives, even world-class athletes experience nerves and anxiety in one form or another.
As Serena's sister Venus Williams said when talking about her sister's experience, "Nerves are normal. You can't be cured from them unless you're a machine."
Sian Beilock, a psychology professor at the University of Chicago and author of "Choke: What the Secrets of the Brain Reveal About Getting it Right When You Have To", agreed that it hardly matters how talented Serena is.
"What it really comes down to is this idea that our success is not just based on our skill," Beilock said. "It's how we're thinking and our anxiety that matters and will really affect whether we fail or shine."
What many find interesting is Williams' penchant for playing badly during early and less consequential stages of a match, then often performing her best following a letdown or when the stakes are highest.
"I just go for it," she explained at Wimbledon this year. "At that point I kind of relax and see whatever happens, happens."
Beilock said Williams is in control at that point because she removes the pressure. "In her own words, she has resigned herself that this might not go well," she said. "She may use it as motivation. Pressure is a subjective thing. Your stress may not be my stress."
Or, as Cliff Drysdale suggested to broadcast partner John McEnroe during Williams' match, (and McEnroe agreed) there is the sudden realization of "Wait a second, I'm John McEnroe" or "I'm Serena Williams" while playing a lesser opponent.
Venus said in her experiences, she just "buckles down" and plays more aggressively.
"It's just about how you deal with it and how you conquer that moment," she said. "You can see it as a burden or see it as something you go through and get used to hopefully."
Six-time doubles and mixed Grand Slam winner Rennae Stubbs said she didn't have many bouts of nerves during her pro career, but one memorable one was when she and doubles partner Sam Stosur were leading 5-2 in the third set of the Wimbledon semis in Stubbs' last Wimbledon in 2009, and Stubbs was serving for the match.
"We fought the whole way and I was relatively relaxed," the ESPN analyst said. "I was nervous but it was a focused nervous, which is different."
The two, known for their service games, were up two breaks. "So in that situation," Stubbs said, "the money would be heavily on us. And then, without explanation, the nerves just went and my arm felt like it just went limp. You just have to go back to 'You can do this. You've done it hundreds, thousands, millions of times.'"
Stubbs said in that situation, breathing and getting your feet moving can also go a long way. "You kind of fight through and your refusal to lose kind of kicks in, and you have to detach from the outcome," she said. "That's the most important thing any athlete can be told."
Mary Joe Fernandez, who won two Grand Slam doubles titles and two Olympic gold medals in doubles, said the most significant stress she has felt came not during her pro tennis career, but before tests in school and playing on the Legends tour.
"You would think 'What's the big deal?' But you get out there and it's funny," she said. "I don't get nervous until I feel like, 'Oh my gosh, maybe we can win this.' I have no expectations and then all of a sudden it's a big point and then it's like, 'Oh my gosh, how I am going to make this shot? Am I going to make this return on the break point?' Or 'You better get this first serve in and not double fault.'
"All these things creep in your head. I think the pressure comes from knowing you can do it. If you don't think you can do it, there's really no pressure."
That could explain the stress that players such as Williams and Nadal experience. Nadal, who has won 14 Grand Slam titles in his career, said earlier this week he has battled nerves "for a lot of moments this year," struggling to explain how it feels.
"When you are hitting a forehand and you don't have the tempo to hit the forehand; if you want to hit the forehand here and you hit the forehand here, it's because you don't have the [mental relaxation]," he said. "You are not enough relaxed in your mind to do what you used to do."
Beilock said it's the old paralysis by analysis theory, "this over-attention to detail," she said. "Their most successful performances happen outside their conscious awareness. They know what to do. But highly skilled athletes can put too much in their heads, too many details."
Williams is considered by many in the game to be the best server in all of tennis, singled out for her perfect toss and precise mechanics as well as her power. But she aborted her service toss several times against Kiki Bertens on Wednesday and also struggled with her toss against 18-year-old Belinda Bencic in a semifinal loss in Toronto in mid-August.
But even when the toss is fine, cautioned Pam Shriver, who has observed Williams closely in her role as an ESPN analyst, problems can arise when trying to keep up the racket speed or to be safe and not serve with too much spin.
"So what you're trying to do and what you do are two totally different things," Shriver said. "I feel that Serena is battling some of that right now."
Shriver said she has found that in tennis, nerves affects hands and arms. "Tennis players always talk about the elbow. But it can be a finger," she said. "The very, very smallest but extra movement and the toss can be four feet off. It's incredible."
Shriver reached the US Open finals at age 16, and won 21 Grand Slam doubles titles and one mixed doubles title in her career, and has both seen and experienced stress on the playing field manifest itself in a variety of ways.
"Everyone's different, and it can come and go," Shriver said. "It can come when you're older. It can come at certain shots. My experience was that it was my toss, so therefore my serve, and my forehand, particularly my forehand volley. I would get very anxious."
At 6 feet tall, Shriver was one of the stronger serve-and-volleyers in the game and describes "a build up of anxiety" on her serve. "It affected both my left hand and my right hand. First 10 years I played, I don't ever remember making a missed toss. And then one day, at a regular tour event, something happened and my left hand didn't coordinate the same way it had the previous 10 years on tour. And then I started wondering."
While some believe there is no way to simulate the actual competitive situation that brings out nerves, Williams tried to get back to basics Wednesday by heading immediately to the practice court after her match and spent most of the hour-and-a-half session serving.
What was overlooked by many in her performance, which included a first-set tiebreaker, is that while Williams may have played poorly in some big moments, her opponent, playing her first career match in Arthur Ashe Stadium, gave away that critical first set after leading 4-0 in the tiebreaker.
And that may be a weapon as big as Williams' serve.
"I think the important thing is to remember [if you're Serena]," Stubbs said, "is who you are, what you've done and remember how hard it is for the person on the other end to beat you."