Roger Federer took a look around as he entered the stadium court at the Miami Open, immediately feeling the energy of the crowd. He gave them quite a show. Federer advanced to the fourth round at Key Biscayne on Monday, beating Juan Martin del Potro 6-3, 6-4. Federer, who was facing del Potro for the first time since 2013, never lost serve and improved to 15-1 this year. He broke del Potro twice, once in each set, and that was all he needed. ''I feel like I earned it more,'' said Federer, the 2005 and 2006 champion on Key Biscayne. ''I was more the aggressor. It was more my racket, and I like it that way.'' The first break put him up 5-3 in the first set, and the fourth-seeded Federer then fought off four break points in the ensuing game before closing out the set. Another break for a 3-2 lead in the second set, not long after del Potro got his oft-problematic left wrist taped on a changeover, put Federer in control. Serving at 4-3, Federer faced a break point - Argentine fans serenaded del Potro beforehand with ''Ole! Ole! Ole!'' - but escaped when a serve return sailed long. ''I did my best,'' the 29th-seeded del Potro said. ''He played well in the break-point moments and I think that was the only difference in the match.'' It had the feel of a final, not a third-rounder on a Monday afternoon. The stadium court, largely empty for the first two matches of the day, was filled - with huge roars greeting both players as they entered for warmups, many fans wearing hats or shirts with Federer's ''RF'' logo, many others either donning Argentine soccer jerseys or carrying that nation's flag in support of del Potro. ''It was really a great, nice atmosphere,'' Federer said. ''It was a lot of pleasure playing in nice weather, great opponent, great crowd. What else do you need?'' The last seven Federer-del Potro matches coming into this meeting all went the distance, with some classics - the 4 1/2-hour, three-setter at the 2012 Olympics at Wimbledon where Federer prevailed 19-17 in the third, Federer rallying from two sets down in the French Open quarterfinals that year, and del Potro winning the 2009 U.S. Open in five sets for his lone Grand Slam triumph. Federer plays again Tuesday against 14th-seeded Roberto Bautista Agut, who needed three sets to top Sam Querrey of the U.S. Other third-round men's winners included top-seeded Stan Wawrinka, eighth-seeded David Goffin, 10th-seeded Tomas Berdych, 12th-seeded Nick Kyrgios, 16th-seeded Alexander Zverev and unseeded Adrian Mannarino. Zverev's match with John Isner of the U.S. lasted just over 2 1/2 hours and needed three tiebreakers - Zverev winning 6-7 (5), 7-6 (7), 7-6 (5), saving three match points in the second set and rallying from a 4-1 deficit in the final breaker. Top-seeded Angelique Kerber made the women's quarterfinals after beating Risa Ozaki 6-2, 6-2. Kerber next meets 11th-seeded Venus Williams, who defeated seventh-seeded Svetlana Kuznetsova 6-3, 7-6 (4) in a matchup of former Miami Open champions. Williams fended off two set points to get into the tiebreaker, and then rallied from 4-1 down in that decider. Caroline Wozniacki reached the quarters when Garbine Muguruza retired after the first set after feeling dizziness that she said was brought on by the heat. Wozniacki, the 12th seed, took that set over the sixth-seeded Muguruza 7-6 (1). ''Happy to be in the quarters,'' Wozniacki said. ''I feel like I'm playing well.'' Following that tiebreaker, which wrapped up a 70-minute set, Muguruza decided she could not continue on a 77-degree, humid afternoon in South Florida. She said she began feeling a headache and stomach pain midway through the set, then experienced some dizziness. ''Kind of went more and more during the match,'' Muguruza said. Wozniacki has not dropped a set during the tournament and will next face Lucie Safarova, who upset fourth-seeded Dominika Cibulkova 7-6, 6-1. Karolina Pliskova also won, topping Czech Fed Cup teammate - and occasional doubles partner - Barbora Strycova 6-1, 6-4. ''I was expecting a tough battle,'' Pliskova said. ''It was tricky in the end.'' Third-seeded Simona Halep dropped the first set before beating 14th-seeded Samantha Stosur. Other women's quarterfinal spots went to 10th-seeded Johanna Konta and 26th-seeded Mirjana Lucic-Baroni (For more sports news and updates, follow Ahram Online Sports on Twitter at @AO_Sports and on Facebook at AhramOnlineSports.)
