NEW YORK -- This one shouldn't have been close.
After all, Eleni Daniilidou of Greece and Australia's Casey Dellacqua had never played a WTA-level match together. And then David slew Goliath. Raymond and Huber, the defending U.S. Open champions, blinked. They lost the extra session 10-8 and, momentum suddenly gone, dropped the first three games of the third set.
"Mentally, we were in and out," Huber said, shaking her head. "It was five different matches today. Error after error. But we fought through that."
Down 4-1, Raymond and Huber finally made the conscious decision to wrest the momentum from Daniilidou and Dellacqua. They won the last five games.
"Those last five games," Huber said, "that's how we play."
Momentum is the very pulse of tennis. Matches can turn on a dime, and they often do.
In terms of physics, linear momentum is an undeniably concrete thing, the product of the mass and velocity of an object. But in tennis, where momentum involves individuals and impacts a course of events, it is more elusive, even mystical.
Tennis, perhaps more than any other sport, lends itself to these dramatic swings, but what's been happening here at the U.S. Open defies explanation.
In the first three days, nine men came back from a daunting two-set deficit. Not only is that amazing, it tied the all-time U.S. Open mark, set in 1989 -- with 11 days left to play. The Open era record of 14, set at the 2002 Australian Open, is at risk.
Snap, crackle, pop! That's how it's been at the Billie Jean King National Tennis Center.
How do you explain what happened Tuesday between American Jesse Levine and Alexandr Dolgopolov? The Ukrainian came into the match as the No. 14 seed in the wake of a terrific summer, including winning the title in Washington, D.C.
And then Levine won the first two sets and took a 4-0 lead in the third. It was a stunning display.
"It was a really good start for me," Levine said Thursday before his doubles match. "He wasn't playing that well, but I was taking him out of his game. Obviously, in third set I had a chance to close it out."
Dolgopolov won 18 of the last 21 games.
"I got a little tentative," Levine conceded. "Once he got control, well, guys at that level don't let go -- that's one thing that separates them. He was so confident, it was tough for me to regroup. In retrospect, I had to do it in the third or the fourth.
"By the fifth set I had let it go. There was no way to get the momentum back."
There's that word again.
Athletes tend to downplay pressure, but for the higher-seeded players, it's there. Dolgopolov, for instance, is new to the upper echelons of tennis and probably felt a powerful urge to prove he belongs. Likewise, Juan Monaco, the No. 10 seed, tightened severely after winning the first two sets against Guillermo Garcia-Lopez. Monaco lost tiebreakers in the last two sets.
Pam Shriver, a longtime player and now ESPN analyst, thinks momentum is contagious.
"I try to look at it from the positive side," she said. "After the first two [0-2] comebacks on Monday, I think guys went out there consciously thinking about it. Like, 'Hey, it's possible, I can do this.' On the other hand, if it's 2-0, and it's in the bag -- what happens when it starts to slip away? 'Wait a minute. Oh my God, this guy's coming back on me.'"
The International Tennis Federation doesn't keep the specific numbers, but 0-2 comebacks are not normal. World No. 1 Roger Federer led Jo-Wilfried Tsonga two sets to love a year ago at Wimbledon -- and suddenly lost his mojo. Federer came in with a staggering 178-0 record when winning the first two sets of a Grand Slam match.
Earlier this month, Federer acknowledged he was "a bit shaken" by the loss to Tsonga. Imagine, the all-time Grand Slam champion among men, feeling something less than invincible.
Small wonder, then, when it happened again in his next major.
Federer, hemorrhaging momentum, lost famously to Novak Djokovic in the U.S. Open semifinals last year after holding two match points. Of course, this year, Federer remastered momentum after dropping the first two sets to Juan Martin del Potro at Roland Garros. The shift was astounding; del Potro won five games in the last three sets.
Why is tennis like this?
Because, in the end, it all comes down to a single person, a single central nervous system. Or two, actually. In a Zen way, momentum is an all-or-nothing force the two combatants are wrestling for. When one loses belief, another invariably finds it.
"You're out there all by yourself," Raymond said. "On the 10, 15 seconds between points, you're completely within yourself -- except for doubles. You're thinking, 'How am I going to win this next point?'
"In singles, there are no teammates to bail you out. When things start to get away from you, sometimes there's no way to correct it."
In this respect, tennis is a lot like golf. Remember Jean Van de Velde? Standing on the 72nd tee, he had a 3-shot lead in the 1999 British Open. He triple-bogeyed the final hole to fall into a playoff. Momentum being momentum, he lost to Paul Lawrie.
Another factor in the record number of 0-2 comebacks is the phenomenal depth in men's tennis. The margins between, say, the No. 20 player and the No. 40 player are remarkably narrow.
Momentum, apparently, is mindless.
Tommy Haas now knows this. He was having a terrific summer and was favored in many minds to beat Ernests Gulbis in their first-round match Wednesday. The 34-year-old Haas won the first two sets and was serving at 3-2 in the third.
"I think I let it slip away a little bit in the third," Haas said later. "That 3-2 game, it's going to stay with me for a little bit, for sure. Just got a little bit tight, a little bit nervous trying to consolidate that break.
"Even in the fourth or the fifth, every time I did have break chances he came up with some great shots, just going for it, like not really thinking about it, which makes him very dangerous."
Indeed, the Latvian came back to stun the No. 21 seed, 3-6, 4-6, 6-4, 7-5, 6-3.
"The mindset is that you don't care anymore," Gulbis explained. "You're two sets down, you're a break down. You simply don't care. Then magic happens suddenly. You win a break back, you win a set and you're back in the match.
"It's nothing too much to think about."
Even the very best players cannot always resist the fickle forces of momentum. Serena Williams, the heavy favorite here, had a first-round match at the French Open against No. 111-ranked Virginie Razzano. Serena won the first set and was up 5-1 in the second-set tiebreaker -- two points from the match -- and let Razzano back in. Ultimately, Serena lost for the first time ever in the first round of a major.
"Tennis is kind of like basketball in that respect," Shriver said. "Maybe it has something to do with the quickness at which the game is played. There's lots of speed. You can be up 15 points and three minutes later it's tied."
Students of the game factor momentum into their thinking. Justin Gimelstob, a Tennis Channel analyst, named Andy Murray and del Potro as his favorites -- based strictly on the fact that they won the last two matches at the Olympics, for the gold and bronze medals.
Can momentum be managed with experience?
"I hope so," said Levine. "I'm trying to take away the positives. I was right there in a match with a guy who was 15 in the world. I was taking it to him. My ranking is a career-high 76. It made me realize I belong out there with the big boys.
"It was a tough pill to swallow, but I swallowed it. I'll be better in that situation next time."