Michael Russell provided an upset on the opening day of the Farmers Classic, ousting sixth-seeded Dimitry Tursunov 6-7 (5), 6-0, 6-2 on Monday.
The American, ranked 110th in the world, overwhelmed his 46th-ranked opponent and set up a second-round clash against compatriot Ryan Harrison.
The result should open up that quarter of the draw for third-seeded Marcos Baghdatis, who received a bye to the second round.
Another American to win was Ryan Sweeting, who beat Somdev Devvarman 6-4, 7-6 (6), avenging a first-round loss to the Indian at Atlanta a week ago.
Sweeting's second-round opponent will be either eighth-seeded Igor Kunitsyn, or the hard-hitting Fernando Gonzalez.
Lu Yen-hsun of Taiwan beat wild card Robby Ginepri of the U.S. 6-4, 7-5, and will next face Baghdatis.
Top-seeded Mardy Fish and No.2-seed Juan Martin Del Potro received byes to the second round.
Daniel Kosakowski advanced to the second round by beating fellow American qualifier Tim Smyczek, 2-6, 6-1, 6-3 and Ernests Gulbis of Latvia upset No. 5 seed Xavier Malisse of Belgium, 2-6, 6-3, 7-6 (5).