KEY BISCAYNE, Fla. -- Andy Murray won Sunday while Ivan Lendl watched as a fan rather than as a coach.
With Lendl among the stadium spectators, Murray advanced to the fourth round at the Sony Open by beating Feliciano Lopez 6-4, 6-1. The tournament is the first for the two-time Key Biscayne champion since he parted with Lendl, who coached Murray for two years and helped him become a Grand Slam champion.
"We're back together again. It was only a four- or five-day split," Murray joked. "No, it's a shame he won't be watching many more of my matches from the stands."
Roger Federer also advanced easily in the upset-free tournament, beating qualifier Thiemo de Bakker 6-3, 6-3. Venus Williams committed 44 unforced errors but had 11 aces and edged wild-card Casey Dellacqua 6-4, 5-7, 6-4.
Lendl helped Murray win Wimbledon, the U.S. Open, an Olympic gold medal and last year's Key Biscayne title. Lendl said he decided to step down because he wanted to concentrate on other projects, among them playing more senior events.
Murray was unhappy about the split and said Lendl will be difficult to replace. Before their partnership, Murray was 0-4 in Grand Slam finals -- although he did win Key Biscayne in 2009.
The No. 6-seeded Murray moved one round closer to a potential quarterfinal against Novak Djokovic. Murray returned well and made the most of his chances at the net to improve to 9-0 against Lopez, seeded 32nd.
The victory came on a sunny, 85-degree afternoon. Murray confirmed it was hot, although the Scotsman -- who lives part-time in nearby Miami -- said Fahrenheit temperatures give him pause because he's more familiar with Celsius.
"I started using Fahrenheit a bit more, but I don't know the conversion," he said. "If I speak to someone back home and they say, `How hot was it?,' and I say, `It's 85 today,' and they say, `What is that?,' I have absolutely no idea."
Murray's next opponent will be No. 11-seeded Jo-Wilfried Tsonga, who outlasted Marcos Baghdatis 4-6, 7-6 (6), 7-5. Tsonga rallied from a 5-1 deficit in the tiebreaker.
Federer didn't face a break point against de Bakker, and after two matches he has lost only 10 points in 20 service games. Federer said a new racket he's using gives him more power, especially on his first serve.
"Right now I'm doing a good job," he said. "But then again, this wasn't Andre Agassi on the other side, or Djokovic. It's just important for me to keep that up and remind myself it's going well so far."
Federer's latest win gave him 43 career victories at Key Biscayne, one more than Pete Sampras and second in men's history only to Andre Agassi's 61.
Williams, a three-time champion seeded No. 29, has won 54 matches on the island. She considers the tournament her home event, because she lives an hour away in Palm Beach Gardens.
Her latest victory took 2½ hours.
"I love being here," she said. "I wanted to play Monday."
Williams' next opponent will be No. 10 Dominika Cibulkova, who beat No. 22 Alice Cornet 7-6 (6), 6-1. No. 11 Caroline Wozniacki lost only five points in the second set and beat No. 17 Sloane Stephens 6-1, 6-0.
Li Na overcame three set points to overtake American Madison Keys 7-6 (3), 6-3. The No. 2-seeded Li, the reigning Australian Open champion, won even though she had seven double-faults and was broken four times.
Keys failed to convert her set points serving at 5-3 in the first set. She also squandered a lead in the second set, when three times she was within a point of going up 3-love against Li.
"She's No. 2 in the world for a reason," Keys said. "She just won Australian Open for a reason. She's a great player. I played well at times, and she just played the bigger points really, really well."
Monday's schedule includes six-time champion Serena Williams against fellow American CoCo Vandeweghe, who rallied past Samantha Stosur 5-7, 7-5, 7-5 in a match that ended at 2:29 a.m. Sunday.