Isner got past Philipp Kohlschreiber 2-6, 7-6 (7-3), 6-2. Kohlschreiber was serving for the match at 5-4 of the second set but Isner posted the first of his three breaks on the day to pull even and then won the tiebreaker.
Isner claimed an early break in the third set and lost just three points on serve in the first set.
No. 12-seeded Nicolas Almagro controlled the third set for a 6-2, 3-6, 6-0 win over Marin Cilic and 13th-seeded Gael Monfils lost his serve just once in a 6-4, 6-1 win over Alex Bogomolov Jr.
Bernard Tomic battled qualifier Santiago Giraldo before emerging with a 4-6, 6-2, 6-4 win and a second-round match against world No. 1 Novak Djokovic. Carlos Berlocq's 6-1, 6-3 victory over Blaz Kavcic pushed him into the next round against No. 2-ranked Roger Federer while David Nalbandian used a 6-3, 6-4 win over Albert Ramos for a second-round pairing against fourth-seeded Andy Murray.
Fernando Verdasco moved into the second round when, after Verdasco took the first set 6-0, Alexandr Dolgopolov retired because of illness.
Other winners Monday were Radek Stepanek, Stanislas Wawrinka and Fabio Baghdatis.