The top-seeded/world No. 1 Federer was leading Robin Soderling 6-4, 3-0 when the Swede retired due to an illness in the second set. Federer fired six aces and tallied three breaks in the brief 47-minute encounter. The Swiss great is now 5-0 lifetime against Soderling.The reigning Wimbledon and U.S. Open champion Federer, who captured this Miami tournament back-to-back in 2005 and 2006, is still seeking his first trip to a final in 2008.
Federer's fourth-round opponent will be Argentine slugger Jose Acasuso, a 6-4, 6-4 winner against Israeli Dudi Sela.
Also making it to round four was American Andy Roddick. Seeded sixth here and the 2004 champion, Roddick converted just two of nine break-point opportunities, but still dispatched Czech qualifier Ivo Minar, 7-6 (7-4), 6-4.
Fourth-seeded Russian Nikolay Davydenko came from behind to beat Italian Simone Bolelli 6-7 (5-7), 7-5, 6-1 on Day 6 at Crandon Park, while an upset came when Julien Benneteau took out his 12th-seeded fellow Frenchman Jo- Wilfried Tsonga 6-3, 6-3. Tsonga was January's Australian Open runner-up to Novak Djokovic.
Russian Mikhail Youzhny, the 11th seed, topped 24th-seeded Spaniard Nicolas Almagro, 7-6 (7-4), 3-6, 7-6 (8-6). Croatian wild card Mario Ancic defeated 18th-seeded Argentine Juan Monaco, 7-6 (7-5), 4-6, 6-1.
Serbian Janko Tipsarevic handled former Aussie Open champion Thomas Johansson of Sweden 6-4, 6-4.
The 2008 Miami champion will claim $590,000.