NEW YORK (AFP) - Roger Federer rolled to his 29th straight US Open match victory and the women shuffled the chairs in the race to knock Ana Ivanovic off her No. 1 perch Friday on a marathon day five of the US Open. Four-time reigning champion Federer extended his brilliant run by breezing past Brazilian Thiago Alves 6-3, 7-5, 6-4 in the second round at Arthur Ashe Stadium. Jelena Jankovic and Elena Dementieva, both of whom have a shot at seizing the No. 1 ranking, beat tough unseeded opponents to reach the fourth round. American eighth seed Andy Roddick was featured in the night session. Roddick had to rally from a shaky first set to defeat Latvian teenager Ernests Gulbis 3-6, 7-5, 6-2, 7-5 in a match that ended in the early morning hours. Federer, who is trying to salvage a season where he has yet to win a title on the hardcourts, has not lost a match at Flushing Meadows since 2003. "This year was difficult because I couldn't really take tournaments off," Federer said. "I always had to chase the rhythm of playing on that particular surface that I was wanting to play on." The 27-year-old Swiss superstar hammered 19 aces and won 80 percent of his first serve points in the two hour, 14 minute match. "I served really well which is a big bonus," Federer said. "I am concentrating on my own game and physically I am fine." Federer seeks to become the only player to win five or more successive titles at two separate Grand Slams. He has had similar success at Wimbledon winning five in a row beginning in 2003. After a record 237 weeks as the world's number one, Federer lost his position to Rafael Nadal on August 18. This is the first time since the 2004 Australian Open that the Swiss has not been the top seed at a Grand Slam. He clinched Friday's match with a forehand flick from the baseline that sailed crosscourt and just caught the line. It has been a rough year for Federer that was punctuated earlier this month when he lost the number one ranking.  Federer, who has reached the semi-finals or better in 17 straight majors, remains two Grand Slam titles shy of tying Pete Sampras' all-time record of 14. On the women's side, world number two Jankovic defeated Zheng Jie of China 7-5, 7-5 in a third round match on Friday. Serbia's Jankovic is the lone top three seed remaining in the women's draw after the stunning upset of top seed Ivanovic on Thursday and the ousting of Russian third seed Svetlana Kuznetsova on Friday.  Zheng, of Cheng Du, made Jankovic work for the win, especially in the final game, which lasted 18 minutes and included 11 deuces. "I had a really bad percentage of first serves," she said. "I was struggling with that stroke. But I managed to win at the end so that is the most important thing." The second-seeded Jankovic moves through to the fourth round where she will play 14th seed Caroline Wozniacki of Denmark. "I felt I had some chance but she had lots of heart," Zheng said. "I was not too bad. I tried to go to the volley and put pressure on her but I felt my serve was not good. I double faulted too much." Jankovic is one of two women's seeds in action Friday who can supplant Serbian Ivanovic as number one if they do well at Flushing Meadows. Jankovic already spent time at number one this year even if it was for just one week. She reached the semi-finals at Wimbledon and the French Open. She would regain that No. 1 WTA ranking if she advances to the semi-finals. Jankovic said she was amazed to hear about Ivanovic's loss. "It's surprising," Jankovic said. "I have no idea how she played, what the other girl did. I have no idea. I only heard it on the news." Fifth-seeded Dementieva needs to advance to the finals to surpass Ivanovic who still has a modest chance of holding on to number one. Russia's Dementieva, who is trying to become the third player to win an Olympic gold medal and the US Open in the same year, defeated rising British star Anne Keothavong 6-3, 6-4. Dementieva booked a date in the fourth round against China's Li Na, who beat Russian Ekaterina Makarova 6-1, 4-6, 6-2 to reach the fourth round. Li missed last year's US Open with a rib injury. Two years ago, Li became the first Chinese woman to reach the fourth round at a US Open. In other men's second round play, Russian fifth seed Nikolay Davydenko defeated Agustin Calleri of Argentina, 6-4, 6-4, 7-6 (7/2) and compatriot Dmitry Tursunov beat Victor Hanescu 6-7 (2/7), 6-3, 6-4, 6-2. Gilles Muller outlasted Germany's Tommy Haas 2-6, 2-6, 7-6 (7/5), 6-3, 6-3.