Top-seeded Rafael Nadal, defending champion David Ferrer, Juan Martin del Potro and John Isner moved into the third round of the Paris Masters on Wednesday.
Nadal beat Marcel Granollers 7-5, 7-5 in an all-Spanish meeting, Ferrer overcame Lukas Rosol 6-0, 2-6, 6-3, and Del Potro beat Marin Cilic 6-4, 7-6 (3).
Nadal broke for a 6-5 lead in each set and clinched the victory when Granollers sent a forehand wide. The match stats pointed to a narrow margin of victory, with Nadal hitting 20 winners to 15 for Granollers and making 23 unforced errors compared to 22 for his opponent.
Nadal was playing at the Paris Masters for the first time since 2009. He missed the tournament for the past three years because of injuries or fatigue.
The U.S. Open champion is seeking a record sixth Masters title in a single season. He will next play last year's runner-up, Jerzy Janowicz of Poland.
Nadal unseated Novak Djokovic atop the rankings by reaching the final of the China Open in October.
Cilic was playing only his second match since the end of his four-month ban for a positive doping test, while del Potro entered the Paris Masters following titles at the Swiss Indoors and Japan Open, plus a runner-up finish at the Shanghai Masters.
Del Potro capitalized on a backhand error from Cilic to break for 5-4 in the opening set. The fourth-seeded Argentine then took a 6-2 lead in the tiebreaker and clinched the victory on another backhand error from Cilic.
Rosol hit 19 winners to only 10 for Ferrer, but the third-seeded Spaniard made 18 fewer unforced errors.
Stanislas Wawrinka, Nicolas Almagro, Gilles Simon and Grigor Dimitrov also won their second-round matches.
Wawrinka defeated Feliciano Lopez 6-3, 3-6, 6-3 to stay in the race for one of the three remaining ATP Finals spots. In the final set, the seventh-seeded Swiss broke Lopez in the second game and did not face any break points.
Isner outlasted Polish qualifier Michal Przysiezny 7-6 (3), 4-6, 6-3.
A semifinalist two years ago, Isner broke for 3-1 in the last set when Przysiezny netted a routine volley. The American hit 27 aces and 47 winners. Isner will next face second-seeded Djokovic.
Simon edged wild card Nicolas Mahut 6-4, 6-7 (5), 7-6 (3) in an all-French meeting, Almagro beat Ivan Dodig 6-4, 6-3, and Bulgaria's Dimitrov overcame Fabio Fognini 6-3, 5-7, 6-2.
Roger Federer just needs to win his opening match against Kevin Anderson later Wednesday to qualify for the ATP Finals for a 12th straight year.