Four-time champion Roger Federer and reigning U.S. Open and Australian Open champion Novak Djokovic reached the quarterfinals, while defending champion and Olympic gold medalist Andy Murray was a third-round upset victim at the $2.825 million Western & Southern Open, the seventh of nine ATP Masters events this year.
The world No. 1 Federer was not broken Thursday in handling promising Aussie Bernard Tomic 6-2, 6-4 in 62 minutes. The Wimbledon champion and Olympic silver medalist was the Cincy titlist in 2005, 2007, 2009 and 2010.
Federer's quarterfinal opponent will be American two-time Cincinnati runner-up Mardy Fish.
Serbia's second seed Djokovic, who is fresh off his Masters title in Toronto last week, rolled to a 6-0 decision in the first set before Russian Nikolay Davydenko retired prior to the start of the second because of a shoulder injury.
Davydenko hit eight double faults and connected on just 48 percent of his first serves.
Meanwhile, French lucky-loser Jeremy Chardy knocked out the third-seeded Murray 6-4, 6-4 on the hardcourts at the Lindner Family Tennis Center. The British star Murray was riding an eight-match winning streak heading into Thursday.
The Wimbledon runner-up lost in straight sets despite firing 10 aces on Day 5, but he also had his serve broken four times while tallying only two breaks in the setback.
Murray was the Cincinnati champ in 2008 and last year, beating Djokovic in both finals.
Another upset saw Canadian Milos Raonic defeat fifth-seeded Czech Tomas Berdych 6-4, 2-6, 6-2. Raonic fired 20 aces and saved 3-of-5 break chances by Berdych to advance to the quarters.
Also on Thursday, sixth-seeded Juan Martin del Potro got past Serb Viktor Troicki 7-6 (7-2), 2-6, 6-1 in 2 hours, 16 minutes, while a 10th-seeded Fish handled Czech veteran Radek Stepanek, 6-3, 6-3.
Up next for the Olympic bronze medalist and former U.S. Open champion del Potro will be Chardy.
Other third-round results saw 12th-seeded Croat Marin Cilic douse Spaniard Pablo Andujar, 7-6 (7-4), 6-2 and Swiss slugger Stan Wawrinka erase 14th- seeded Japanese Kei Nishikori, 6-3, 6-3.