Murray, ranked No. 4 in the world, reached the fourth round at the California event for a third straight year by beating Frenchman Paul-Henri Mathieu 6-3, 6-2. Murray, 21, is 17-1 so far this season.
In other Monday action, 10th-seeded Spaniard Fernando Verdasco beat 23rd-seeded Frenchman Richard Gasquet 6-3, 6-2 and 17th-seeded Chilean Fernando Gonzalez beat 13th-seeded American James Blake 7-5, 6-1.
Also, German Philipp Kohlschreiber defeated Ecuador's Nicolas Lapentti 6-2, 3-6, 6-3.