Isner had to go to the tie-breaker before finally winning the match over the seventh-seeded Becker and moving on to face Marco Baghdatis of Cyprus.
Baghdatis, a finalist in this year's Australian Open, beat Canadian Frank Dencevich 7-6 (3), 6-3.
Russian Marat Safin rallied to beat Robby Ginepri of the United States 3-6, 6-3, 6-4 and will face Ernest Gulbis of Latvia Wednesday.
Copyright 2009 by United Press International.