NEW YORK (AP) -- More than three years have passed since Roger Federer won a Grand Slam title.
That's not to say he hasn't played well in the meantime: As he likes to point out, it takes some doing just to make it to the latter stages of a major tournament, and Federer has managed to continue to do that.
His seemingly effortless trip to the U.S. Open semifinals -- Federer has won all 15 sets he's played entering Friday, dropping only 44 games along the way -- marks his sixth run to that round in the past 11 majors.
And yet when Federer was asked about being two wins away from grabbing another trophy, he noted that there is plenty of work left.
"Hours of work and sleeps and waits and nerves and all that. It's still a long way," Federer said. "I feel like I'm close, of course. You enter now a territory which is very interesting."
On Friday, the No. 2-seeded Federer will face No. 5 Stan Wawrinka in a matchup pitting a pair of pals who won a gold medal for Switzerland in doubles at the 2008 Beijing Olympics. That will come after No. 1 Novak Djokovic meets No. 9 Marin Cilic, the defending champion.
They form quite a quartet.
It's the first time since 1995's group of Pete Sampras, Andre Agassi, Jim Courier and Boris Becker (who now happens to coach Djokovic) that all of the U.S. Open men's semifinalists have won a Grand Slam title.
Federer, of course, leads the way among this year's foursome with a record 17, including five in New York.
Djokovic has won nine major titles, including at the Australian Open and Wimbledon this season, but despite reaching his ninth consecutive semifinal at the U.S. Open, he's only left with a trophy once, in 2011.
Wawrinka is a two-time major champion, including at the French Open in June.
And Cilic's only appearance in a Grand Slam final came at the U.S. Open a year ago.
"These guys that are left in the tournament," Cilic said, "they are very dangerous."
None has looked better, match in and match out, than Federer so far. He has won 67 of his 69 service games, saving 9 of 11 break points. Only one opponent, 29th-seeded Philipp Kohlschreiber in the third round, managed to break Federer.
Only once before, at the 2011 U.S. Open, has he dropped as few as 44 games on the way to a major's semifinals without getting the benefit of a retirement or walkover.
And only once, at the 2007 Australian Open, has Federer won a Grand Slam title without losing a set.
Now he takes on Wawrinka for the 20th time. Federer is 16-3; all of Wawrinka's head-to-head victories came on red clay, including in the quarterfinals at Roland Garros this year.
"I will, for sure, need to play my best tennis," Wawrinka said about facing Federer. "He's playing really well so far. He loves to play. He knows how to play. ... It's going to be a big challenge. I think I'm ready."
At least he's beaten his semifinal opponent. Cilic has lost every match against Djokovic, 13 in all.
"I'm sure he's not going to start coming to the net after every ball, but I'm sure he's going to try to be aggressive, going to try to take his chances. That's how he won last year's U.S. Open," Djokovic said. "I watched him play. He played great. Best tennis of his life. This is where he loves playing."
Here's what else to watch Friday at the U.S. Open:
Serena Williams' bid for tennis' first calendar-year Grand Slam since 1988 resumes Friday, when she plays 43rd-ranked Roberta Vinci of Italy in the semifinals. No. 2 Simona Halep faces No. 26 Flavia Pennetta in the other semifinal. Both matches were originally scheduled for Thursday night, but were postponed hours ahead of time because of rain in the forecast. Showers did eventually arrive, a little more than an hour before Williams and Vinci were supposed to begin.
Follow Howard Fendrich on Twitter at http://twitter.com/HowardFendrich