Roger Federer has reached the U.S. Open semifinals for the first time since 2011 , but he sure had to do it the hard way . Federer saved two match points and rallied from two sets down to defeat enigmatic Frenchman Gael Monfils 4-6 3-6 6-4 7-5 6-2 in a late-night thriller in New York . The two played in Cincinnati just a few weeks ago and Monfils stretched Federer to a deciding third set . He was even closer to upsetting the 17-time grand slam champion under the lights at Arthur Ashe Stadium on Thursday , holding two match points on Federer 's serve at 5-4 in the fourth . While Federer saved the second match point with a winning forehand , Monfils had an opportunity on the first match point , only to miss a backhand long . Monfils never recovered . He double faulted twice to drop serve in the next game , Federer held to claim the set and the 33-year-old then cruised in a quick fifth set . It was the ninth time in his career Federer came back from two sets down . The last time it happened was at Wimbledon in 2012 -- against another Frenchman , Julien Benneteau . In a potentially good omen for Federer , he went on to win the title at the All England Club -- his last success at a major . `` I got off to a good start , so I was actually feeling alright , but then when I was down two match points , that 's when I was n't feeling so great anymore , '' Federer , 28-1 in night session matches at the U.S. Open , said on court afterwards . `` I thought , 'This is it . This is the last point , man , just go down fighting , do n't miss an easy shot and let him have it . ' `` But I served well and stayed in the match and somehow turned it around . I felt great in the fifth , though . `` I was really starting to play better and better as the match went on , and that 's a great feeling . '' Federer faces the resurgent Marin Cilic in Saturday 's semifinals after the big-serving Croat dispatched Czech sixth seed Tomas Berdych in straight sets . A year ago Cilic sat out the U.S. Open due to a doping suspension . The other semifinal sees top seed Novak Djokovic meet Japan 's Kei Nishikori , a maiden grand slam semifinalist . They won their quarterfinals Wednesday . For Monfils and France , it marks more disappointment . The country 's wait for a men 's grand slam singles champion will extend to 32 years . `` I will need time to forget about this match , but it gives me more motivation , '' the 24th-ranked Monfils was quoted as saying by L'Equipe . `` He ( saved ) those two ( match points ) , so bravo to him . After that it was hard because my serve was n't good . He played well and me , I had a ( dip ) for five minutes . `` I felt tired physically and mentally , too , and he was very aggressive at that time . '' Serena Williams and pal Caroline Wozniacki will meet in the women 's final if they both -- as expected -- progress Friday . Williams , the only grand slam singles champion of the women 's semifinalists , plays Russian left-hander Ekaterina Makarova and former No . 1 Wozniacki plays China 's Peng Shuai . Makarova , though , owns a grand slam win over Williams at the Australian Open in 2012 .
Roger Federer rallies from 5 sets down to beat Serena Williams in New York . Monfils held two match points on Croatian Marin Cilic 's serve at two -4 in the fourth set . The Swiss next meets resurgent Croatian Marin Cilic in the semifinals . Serena Williams plays Roger Federer in the women 's semifinals Friday .