Landmark win for Lleyton
Lleyton Hewitt came back from a set down to claim his 600th ATP Tour win and set up a Sony Open second-round clash with top seed Rafael Nadal.
The Australian, the 2001 US Open and 2002 Wimbledon champion, trailed Holland's Robin Haase after losing the opening set 6-3 but won each of the next two by that same scoreline to progress.
Hewitt becomes the 21st player to record 600 wins on the tour but only the third among active players, with Roger Federer having won 942 matches and Nadal 675.
There were no such celebrations for compatriot Bernard Tomic, though, the youngster brushed aside 6-0 6-1 by Finn Jarkko Nieminen in 28 bewildering minutes.
Sam Querrey rewarded the American fans who stayed until the end of the day's play with a 7-6 (7/2) 6-3 win over Sergiy Stakhovsky, disposing of the Ukrainian in 74 minutes with two breaks in the second set.
Three other home players progressed, with Ryan Harrison, Jack Sock and Donald Young beating Argentinians Federico Delbonis, Guido Pella and Carlos Berlocq respectively, but Steve Johnson and Bradley Klahn lost to Spaniards Roberto Bautista Agut and Guillermo Garcia-Lopez.
France's Edouard Roger-Vasselin beat Igor Sijsling 3-6 6-3 7-6 (7/3) but compatriot Nicolas Mahut lost 7-6 (10/8) 7-6 (7/2) to Denis Istomin.
There were also wins for Daniel Gimeno-Traver, Yen-Hsun Lu, Lukas Lacko, Aljaz Bedene, Joao Sousa and Stephane Robert.
In the women's event, top seed and home favourite Serena Williams was taken to a lengthy first-set tie-break but was ultimately comfortable in beating Kazakhstan's Yaroslava Shvedova 7-6 (9/7) 6-2 to reach the third round.
Maria Sharapova had no trouble getting past Japan's Kurumi Nara, the Russian breaking serve five times to Nara's two in a 6-3 6-4 win.
All the players seeded in the top 20 progressed, though fifth seed Angelique Kerber needed a third-set tie-break before she finally saw off China's Shuai Peng 6-3 1-6 7-6 (7/5).
Petra Kvitova beat Paula Ormaechea 6-3 6-4 while Sara Errani, seeded one place lower at nine, got past Patricia Mayr-Achleitner 6-1 6-4.
Ana Ivanovic ended the hopes of American Lauren Davis, winning 6-1 6-1, while Sabine Lisicki came from a set down to beat wild card Nadia Petrova 3-6 6-4 6-4.
There were three seeds eliminated, with Anastasia Pavlyuchenkova the highest at 21 as qualifier Coco Vandeweghe delighted the home fans with a 7-6 (9/7) 7-5 win.
Tsvetana Pironkova beat 25th seed Sorana Cirstea 6-3 6-3 while Carolina Garcia saw off Klara Zakopalova in two tie-breaks.
And 17-year-old Croatian qualifier Donna Vekic marched on with a 7-6 (7/5) 7-5 win over Svetlana Kuznetsova, the 28th seed.
Sam Stosur, Ekaterina Makarova, Kirsten Flipkens, Lucie Safarova and Flavia Pennetta all went safely through, with Flipkens the only one of the quintet to drop a set.