Third-seeded Roger Federer was a second-round winner Tuesday at the $2.43 million Western & Southern Open, an ATP Masters and U.S. Open Series event.

Federer took down Argentine Juan Martin del Potro 6-3, 7-5 on the hardcourts at the Lindner Family Tennis Center.

Federer titled here for a fourth time by edging out American Mardy Fish in last year's Cincy finale.

It was del Potro who stunned Federer in the 2009 U.S. Open final.

Other second-round wins came from eighth-seeded Czech Tomas Berdych and American James Blake. Berdych beat Argentine Juan Monaco 7-6 (7-2), 6-0, while Blake, the Cincinnati runner-up in 2007, defeated Italian Fabio Fognini 6-4, 6-2.

Ninth-seeded Nicolas Almagro got past fellow Spaniard Albert Montanes 7-6 (7-5), 6-4 to reach the second round; 10th-seeded Frenchman Gilles Simon overcame Austrian Jurgen Melzer 6-7 (3-7), 6-3, 7-5; French left-hander Michael Llodra doused 13th-seeded Russian Mikhail Youzhny 7-5, 3-6, 7-6 (7-4); 15th-seeded Frenchman Jo-Wilfried Tsonga, a Wimbledon semifinalist last month, beat struggling Croat Marin Cilic 6-3, 6-4; and Kazakhstan's Andrey Golubev upended 16th-seeded Swiss Stanislas Wawrinka 3-6, 6-4, 6-1 in first-round play on Day 3.

In other opening-round play, former top-five star Nikolay Davydenko of Russia topped Ukrainian Sergiy Stakhovsky 6-2, 7-6 (7-5), Serb Janko Tipsarevic held off French qualifier Edouard Roger-Vasselin 6-0, 3-6, 7-6 (7-5), and 6-foot-10 Croat Ivo Karlovic swatted 19 aces in beating German Florian Mayer 6-1, 6-3.

Resurgent Czech Radek Stepanek, a qualifier this week, continued his recent winning ways with a 7-5, 5-7, 7-6 (7-4) opening-round victory over 6-foot-9 American John Isner. Stepanek was a surprise titlist in Washington D.C. two weeks ago.

Additional first-round wins came for French qualifier Julien Benneteau, Croat Ivan Dodig and Kevin Anderson of South Africa. Benneteau draws former No. 1 Rafael Nadal in his next assignment.

The top seeds here are high-flying Serb Novak Djokovic and Nadal. The 2008 and 2009 Cincinnati runner-up Djokovic defeated the aforementioned Fish in last week's Masters finale in Montreal.

This is the final Masters event before the U.S. Open, which will commence August 29 in New York.

This week's winner will collect $496,000.