FLUSHING MEADOWS, N.Y. -- Reigning four-time champion Roger Federer extended his U.S. Open winning streak to 29 straight matches with a second-round victory Friday at the fourth and final major of the year.

The second-seeded Federer handled Brazilian qualifier Thiago Alves 6-3, 7-5, 6-4 at Ashe Stadium. The 12-time major champion from Switzerland hasn't lost here since the fourth round back in 2003.

Federer fired 19 aces at a game Alves, who was able to keep things relatively close while the Swiss scattered an uncharacteristic 46 unforced errors in a two- hour, 14-minute affair.

The Wimbledon and French Open runner-up Federer beat reigning Australian Open titlist Novak Djokovic in last year's U.S. Open finale.

Federer had been ranked No. 1 in the world since February 2004 before being supplanted at the top by reigning Wimbledon, four-time French Open and Olympic titlist Rafael Nadal on Aug. 18.

Meanwhile, fifth-seeded Russian Nikolay Davydenko doused Argentine Agustin Calleri 6-4, 6-4, 7-6 (7-2) on Day 5 at the USTA Billie Jean King National Tennis Center.

Former Australian Open runner-up Fernando Gonzalez also moved on, as the Chilean slugger handled American Bobby Reynolds 7-6 (8-6), 6-4, 6-4. The 11th- seeded "Gonzo" was an Olympic silver medalist in Beijing earlier this month.

Eighteenth-seeded Spaniard Nicolas Almagro cruised past American Sam Warburg 6-3, 6-4, 6-4, while 23rd-seeded Russian Igor Andreev erased Frenchman Jeremy Chardy 7-6 (7-3), 6-4, 6-3 and American Robby Ginepri lost to 30th-seeded 6- foot-5 Croatian teenager Marin Cilic 6-4, 2-6, 6-2, 7-5. Ginepri was a semifinalist here three years ago.

A pair of unseeded men overcame two-set deficits on Friday, as Luxembourg's Gilles Muller came all the way back to stun former top-five star Tommy Haas of Germany 2-6, 2-6, 7-6 (7-5), 6-3, 6-3 and Finn Jarkko Nieminen fought his way past Czech Ivo Minar 6-7 (2-7), 3-6, 6-4, 6-3, 6-2. The talented but oft-injured Haas reached the quarterfinals here the last two years and is still seeking that elusive first-ever trip into a Grand Slam final.