Andy Murray earned a 5-7, 6-2, 6-2 win over Evgeny Donskoy in a second-round match at the BNP Paribas Open on Sunday.
Mardy Fish of the United States earned a 6-3, 3-6, 6-4 win over Bobby Reynolds.
Fish played his first competitive match of the year after not playing since last September because of a heart condition.
"It's been a tough few months, for sure. You sort of feel like it was a win just to go back out there," Fish said.
"There's a lot of people that have sort of dealt with what I've dealt with and not come back. It's nice to just play, first and foremost, and then you get out there and you want to win.
"You want to stay within yourself a little bit and not get too fired up or too low or too high or anything like that. Then all of a sudden you find yourself in the third set, you know, deep in the third set losing (4-2), and some of that sort of fight starts kicking in and you want to win.
"I certainly didn't expect to win so soon. The tennis side of it hasn't been an issue. I have been playing for quite a while now, as far as months are concerned, but just competitive matches, you can't duplicate those."
Fish lost only three points in the winning the final four games.
He hasn't disclosed the precise nature of his problem because "it's not something that's very easy to talk about."
"I'm going to play Miami (next week)," he said, "and then I'm going to assess it after that, Maybe step back and see how I feel, where I am personally, see after these two weeks if it's something I can still do at a high level. That will certainly be a question I'll ask. Hopefully I'll resume sort of a normal schedule, but we'll see."
In other early men's matches, Marinko Matosevic of Australia upset No. 14 Juan Monaco of Argentina 7-5, 6-0; Bjorn Phau of Germany beat No. 25 Jeremy Chardy of France 6-2, 2-6, 6-4; No. 12 Marin Cilic of Croatia overcame Albert Ramos of Spain 7-6 (7), 6-2; and Yen-hsun Lu of Taiwan beat No. 26 Martin Klizan of Croatia, 7-6 (5), 7-6 (5).
In early third-round women's matches, No. 6 seed Sara Errani of Italy won in straight sets over Johanna Larsson of Sweden 6-3, 6-1; No. 13 Maria Kirilenko of Russia beat American qualifier Mallory Burdette 6-3, 4-6, 6-2; and No. 19 Klara Zakopalova of the Czech Republic beat No. 12 Dominika Cibulkova of Slovakia 6-4, 7-5.