Novak Djokovic rallied from a set down Thursday to beat John Isner 6-7 (5), 6-1, 6-2 and reach the quarterfinals of the Paris Masters.
Djokovic next plays Stanislas Wawrinka, who stayed in contention for one of the two remaining ATP finals spots by defeating Nicolas Almagro of Spain 6-3, 6-2.
Roger Federer also moved into the quarterfinals by dismissing Philipp Kohlschreiber of Germany 6-3, 6-4.
Federer, who won the Paris Masters in 2011, next faces Juan Martin del Potro in a rematch of last weekend's Swiss Indoors final. The fourth-seeded Argentine overcame Grigor Dimitrov of Bulgaria 3-6, 6-3, 6-4.
Defending champion David Ferrer also advanced, beating Gilles Simon of France 6-2, 6-3.
Isner saved six break points to force the early tiebreaker and took the first set when Djokovic's backhand sailed wide. The second-seeded Serb raised his game in the second set, making only two unforced errors and breaking Isner twice.
"I just needed to be very tough mentally and just believe I can make a break," Djokovic said. "I knew as soon as I make a break I'm going to start playing better and relaxed in a way, so that's what happened."
Djokovic then won the last five games of the match, finishing off the American with a backhand volley.
Djokovic stretched his winning streak to 14 matches after taking the China Open and the Shanghai Masters titles in October.
"In China, I have had probably the best two weeks of the year, except at the beginning of the year, so it gives me a lot of confidence," Djokovic said. "I feel that I'm back mentally where I need to be, and hopefully I can maintain this winning streak."