NEW YORK -- Novak Djokovic likes to say that his tear to a 66-2 record and the No. 1 world ranking, which he locked down for the first time by winning Wimbledon, has more to do with his improved mental approach than any change in his strokes or strategy.
Which should make his U.S. Open semifinal Saturday against third-ranked Roger Federer -- the next-to-last man in the way of Djokovic's third 2011 Grand Slam title in four tries -- the most fascinating mind-game challenge Djokovic has faced this year.
Federer is the only man to defeat Djokovic in a match this year that Djokovic played to completion. Three weeks ago, Djokovic was trailing Andy Murray 6-4, 3-0 in the final in Cincinnati when he retired with a shoulder injury that, he says, has not troubled him here.
If not for his shoulder letting him down, the only thing standing between Djokovic and an unheard-of perfect record nine long months into this calendar year would be his four-set loss to Federer in the semifinals of the French Open.
So as good as Saturday's other semifinal showdown between Great Britain's Murray and defending Open champion Rafael Nadal could turn out to be, it can't match Djokovic-Federer for prematch intrigue.
"We have had particularly good matches here at the U.S. Open," Federer said Thursday, "and I have the feeling it's going to be something similar again."
Djokovic brought a daunting 43-match winning streak into their French Open semi. He seemed to have Federer on the ropes after shrugging off how Federer won the first two sets, rallied to seize the third and then seemed to be on his way to forcing a winner-take-all fifth set when he broke Federer to take a 5-4 lead in the fourth. But Federer broke Djokovic back the very next game, then outdid Djokovic in the tiebreaker to grab the match as suddenly as it seemed to be slipping away.
It was great, riveting, seesawing tennis. And to be honest, there was significant doubt right down to the last stroke about whether Federer could pull it off.
By the end, with darkness falling over Roland Garros, the French crowd was loudly chanting Federer's first name.
Nobody watching that day -- or here in New York now, for that matter -- is sure how many more of those throwback performances Federer has left in him at age 30.
The last 30-something man to win a Slam was Andre Agassi at the 2003 Australian Open. Djokovic has nine titles this year; Federer has only one.
Federer also is fighting to avoid finishing a calendar year without at least one Slam title for the first time since 2002. But if Djokovic is able to get past Federer and win it all, he'd become only the seventh man in history to win three majors in the same year, and he might have done it by beating two of the six other players who have pulled it off: Federer and Nadal.
Djokovic is 3-1 overall against Federer this year and beat him in last year's U.S. Open semis. Djokovic says he knows what he has to do against Federer to avoid losing to him Saturday: "I think I need to step on the court in the next match and just be close to the [base]line, be more aggressive. I think the last two matches, I have been starting very slow."
Federer agrees with Djokovic's contention that whoever is stronger mentally is more likely to win. Then, in so many words, he added: Bring Djokovic on.
"He's been having an amazing season, so far," Federer said, "so it's a challenge right now in the men's game. That's what I like, and who I like to play against.
"I've been very dominant. ... I'm looking forward to it."
ANDY MURRAY'S KARMA GLITCH: Murray made people laugh the past few days by being brutally, comically honest about his fervent wish that more rain and marathon-length matches -- preferably both -- would bother the three other semifinalists before he had to play any of them.
"Yeah, I hope it rains on him. ... I hope it rains," Murray deadpanned before Federer's straight-set quarterfinal win over Jo-Wilfried Tsonga on Thursday night in, alas, just 1 hour, 53 minutes and before (heavy sigh) Nadal's straight-set bulldozing Friday of American Andy Roddick in an identical 1 hour, 53 minutes.
Murray needed 3 hours, 24 minutes Friday to hold off John Isner.
Murray's rationale was he'd welcome any help he could get to survive having to play three matches in three straight days just to get to the Open final.
It's the same gauntlet Nadal is facing, because their side of the draw was rained out Tuesday and Wednesday. Although the USTA decided to give the men's finalists a day and move this year's men's final to Monday, Federer and Djokovic still got to enjoy an extra day off Friday while Murray and Nadal had to play.
"It's clearly an advantage [for them]; anyone in sport will tell you that," Murray said, shrugging.
"That's not fair, but that's what it is," Nadal agreed.
Nadal, like Federer, is playing for a chunk of history here. If he defends his 2010 U.S. Open title, it would give him 11 Grand Slam singles championships overall, moving him into a tie with Bjorn Borg and Rod Laver for the fourth-highest total all time, trailing only Roy Emerson (12), Pete Sampras (14) and Federer (16).
Nadal noted Murray did beat him here in 2008. But he likes how he's played better as the Open has gone on.
"I have to play my best tennis, I have to play aggressive, otherwise I don't have a chance," Nadal said. "I'm very happy with my U.S. Open. I'm doing a lot of things better. ... And I have the feeling I can win -- probably even more important."