LONDON — Roger Federer is still rolling in his pursuit of his first Olympic singles medal.
Federer beat American John Isner 6-4, 7-6 (5) and will play No. 8-seeded Juan Martin del Potro in the semifinals.
Serena Williams, another reigning Wimbledon champion who is seeking her first Olympic singles medal, advanced by beating former No. 1 Caroline Wozniacki of Denmark 6-0, 6-3. Williams' opponent in today's semifinals will be top-seeded Victoria Azarenka, who beat Angelique Kerber 6-4, 7-5.
Russians Maria Sharapova and Maria Kirilenko will meet in the other women's semi.
Novak Djokovic also advanced on the men's side and next plays Britain's Andy Murray.
CYCLING: Germany's Miriam Welte and Kristina Vogel checked a computer screen several times before erupting in laughter.
Yup, Olympic champions.
Welte and Vogel won the gold in sprint track cycling after the Chinese duo of Guo Shuang and Gong Jinjie was disqualified for a lane change in the final.
The Chinese pair had finished a victory lap and was celebrating when the announcement was made.
Britain broke its own world record set earlier in the day to win its second straight gold medal in the men's team sprint. The team of Philip Hindes, Jason Kenny and Chris Hoy posted a time of 42.600 seconds, bettering the mark of 42.747 they had set in the previous round.
BEACH VOLLEYBALL: All four American teams — two in the men's tournament and two in the women's — finished the round-robin atop their pools, with defending gold medalists Todd Rogers and Phil Dalhausser beating the Czech Republic in the finale.
Defending world champions Emanuel and Alison of Brazil struggled through an extended first set to beat Italy and win their group. The Brazilians beat Paolo Nicolai and Daniele Lupo 26-24, 21-18.
Americans Jennifer Kessy and April Ross finished 3-0 with a 21-19, 19-21, 19-17 victory over Spain.
WATER POLO: Tony Azevedo scored four goals and the U.S. men's team beat Britain 13-7 to remain undefeated at the London Games.
Gold-medal favorite Serbia played to an 11-11 draw with Montenegro. The Serbs face the U.S. on Saturday.
Spain, Greece, Hungary and Croatia all won.