Rome, Italy -- (Sports Network) - World No. 1 superstar Roger Federer, Australian Open champion Novak Djokovic and former top-ranked American Andy Roddick led the charge into the quarterfinals at the $3.5 million Italian Masters, a clay-court French Open tune-up.

The 2003 and 2006 Rome runner-up Federer held off 6-foot-10 Croatian Ivo Karlovic 7-6 (7-4), 6-3 to come within two wins of his third trip to the final here in six years.

The 12-time Grand Slam champion Federer's quarterfinal opponent on Friday will be gritty Czech Radek Stepanek, who got past Peruvian qualifier Luis Horna 6-4, 1-6, 6-3 on Day 4 at Foro Italico.

Meanwhile, a third-seeded Djokovic outlasted Russian Igor Andreev 6-3, 3-6, 6-3 in a grueling 2 hours, 42 minutes and a sixth-seeded Roddick handled Italian crowd favorite Simone Bolelli 7-6 (7-5), 6-3. Bolelli was last week's Munich runner-up to Chilean strongman Fernando Gonzalez, who was last year's Rome runner-up to Spanish clay-court wizard Rafael Nadal.

An upset came when 14th-seeded Spaniard Tommy Robredo edged out fourth-seeded Russian Nikolay Davydenko 4-6, 6-2, 7-6 (7-4) in 2 hours, 41 minutes in Thursday's nightcap. Robredo is rewarded with a quarterfinal against Roddick.

In other third-round action, eighth-seeded American James Blake overcame Spaniard Fernando Verdasco 5-7, 7-5, 6-2 and Swiss Stanislas Wawrinka waltzed past former world No. 1 Juan Carlos Ferrero 6-4, 6-3. The former French Open winner and 2001 Rome champion Ferrero stunned his fellow Spaniard Nadal in straight sets here on Wednesday. Nadal was the reigning three-time Rome titlist.

Blake, who will appear in his first quarterfinal here since 2002, will battle the capable Wawrinka on Friday.

Spanish clay-court specialist Nicolas Almagro moved into the round of eight via walkover when a 12th-seeded Gonzalez pulled out, citing a right leg injury. "Gonzo" was fresh off his clay-court title in Munich. Almagro will meet Djokovic here on Friday.

This week's winner will take home $558,000.