Big-serving American John Isner stunned Roger Federer to reach the quarterfinals of the Paris Masters Thursday. Isner won 7-6 (7-3), 3-6, 7-6 (7-5) for just his second career win over the Swiss legend. Federer, who won the tournament for the only time in 2011, dropped an opening set tie-break 7-3 before battling back with three games in a row to win the second 6-3. The deciding set again saw serves on top with Federer failing to convert a rare break point at 3-3. He then twice served successfully to stay in the match to force another tie-break. Isner took a 4-1 lead after Federer netted an overhead backhand smash and a backhand into the net from the 17-time major tournament winner handed the giant American four match points. He converted the last of those for the biggest upset so far in the tournament. Isner will play David Ferrer for a semifinal spot after the Spanish eighth seed outlasted Grigor Dimitrov of Bulgaria 6-7 (4-7), 6-1, 6-4 in another third round tie. Earlier in a prelude to this month's Davis Cup final, Andy Murray routed David Goffin 6-1, 6-0 to reach the quarterfinals at the Masters while top-ranked Novak Djokovic advanced in straight sets. Murray lost only eight points on his serve and broke the 16th-seeded Belgian five times. Murray and Goffin are expected to face each other again in the Davis Cup final between Britain and Belgium in Gent from Nov. 27-29. Thursday's match was played on an indoor hard court, but the host Belgians opted to play on clay in the Davis Cup. The second-seeded Murray will next face Richard Gasquet of France, who advanced when Kei Nishikori of Japan retired while trailing 7-6 (3), 4-1. Nishikori received a back massage at the changeover before stopping in the next game. Djokovic booked his spot in the quarterfinals with a 6-3, 7-5 win over 14th-seeded Gilles Simon that extended the Serb's unbeaten streak to 19 matches and 26 sets in a row. On Wednesday, Federer had raced into the third round with an exhilarating display of attacking tennis, thrashing Italian Andreas Seppi of Italy 6-1, 6-1 in just 47 minutes. Crowd favorite Jo-Wilfried Tsonga, the champion in 2008, provided a perfect finish for the Paris fans with a 6-2, 6-2 win over Spain's Roberto Bautista Agut. Venus in semis In China, top-seeded Venus Williams rallied to beat Saisai Zheng of China, 4-6, 6-1, 6-1 and advance to the semifinals of the WTA Elite Trophy Thursday. Venus hit six aces and saved two of four break points against Zheng, who entered the tournament on a wild-card berth. Zheng raced to a 5-1 lead in the first set with aggressive groundstrokes. Venus caught up to 5-4 before the Chinese player closed the opening set after 44 minutes. The win extends Venus' record to 2-0 in Group A. Svetlana Kuznetsova kept alive her slim chances of reaching the semifinals when fifth-seeded Caroline Wozniacki retired from their round-robin match. After Kuznetsova won the first set 7-5, Wozniacki quit at 2-2 in the second with a left wrist injury. Third-seeded Karolina Pliskova beat sixth-seeded Sara Errani 6-0, 6-3. The tournament brings together 11 of the top players who did not qualify for last week's WTA Finals in Singapore, including Wozniacki, Jelena Jankovic and Roberta Vinci. The qualifiers compete in a four-group round robin format, with the winners of each group advancing to the semifinals. One player from the field can move into the Top 10 Monday. Venus is in contention for that spot with Carla Suárez Navarro, Karolina Pliskova and Vinci. — Agencies