British number one Dan Evans beat Kevin Anderson to set up a second-round meeting with compatriot Cameron Norrie at the San Diego Open.
Evans battled through a 77-minute opening set to beat the former world number five 7-6 (13-11) 7-5.
World number 28 Norrie beat 22nd-ranked Evans in the first round of the Australian Open earlier this year.
Fellow Briton Harriet Dart was beaten in the second round of the Chicago Fall Tennis Classic.
Dart, who beat Beatriz Haddid Maia after being added to the main draw as a lucky loser, lost 6-3 6-4 to Russian 12th seed Veronika Kudermetova.
Evans will face Norrie on Thursday, with Andy Murray also in action against 10th seed Casper Ruud.