MELBOURNE, Australia -- Serena Williams cautiously walked onto the court, and tried to keep the points short to avoid irritating her injured right ankle as she advanced to the third round at the Australian Open.

Apart from a swollen lip from hitting herself in the face with her racket in the sixth game, she emerged unscathed.

Summoning all her experience from 15 major titles, including the final two of the last season, Williams lifted her tempo on the biggest points -- winning an 18-minute game to open the second set, finally cashing in on her fourth break chance.

Nineteen minutes later, she finished off a 6-2, 6-0 win Thursday (Australia time) over No. 112-ranked Garbine Muguruza with an ace at 128.7 mph -- the fastest she can remember serving.

"I'm on the up and up, I feel. It can only get better from here," Williams said, adding that she wasn't bothered by the ankle during the match. "Obviously when you go out to play you're heavy on adrenaline and you're really pumped up," she said. "Usually I feel injuries after the match, but so far, so good. I felt pretty much better than I ever dreamed of expecting to feel."

Williams said she was bleeding from the lip at one stage, "But it's OK. It's a war wound."

"I think it happens to everyone, but I have never busted it wide open like that," she said. "So, yeah, I was like, 'Oh, no. I can't have a tooth fall out.' That would be horrible."

Despite the injury concerns ever since needing medical timeout to treat her ankle during her first-round win on Tuesday, Williams planned to play doubles later with sister Venus, and will play her next singles match against Japan's Ayumi Morita on Saturday.

Defending champion and top-ranked Victoria Azarenka practically danced into Rod Laver Arena for the match before Williams' victory, and said she's starting to find some rhythm after beating Eleni Daniilidou 6-1, 6-0 in 55 minutes.

"I felt like I'm back into the competitive mode," Azarenka said. "I was really focused -- that was for sure the best part of the game for me."

The temperature hit 93 degrees during the first match of the day, and went as high as 106 later in the afternoon. Players wore ice vests and were shielded by umbrellas during the breaks in play.

The heat didn't seem to bother 42-year-old Kimiko Date-Krumm, who advanced 6-2, 7-5 over Shahar Peer of Israel. She's the oldest woman to win a singles match at the Australian Open.

Caroline Wozniacki defeated Donna Vekic of Croatia 6-1, 6-4. Wozniacki played her 72-minute match during the hottest part of the afternoon when the temperature peaked at 106.

U.S. Open champion Andy Murray had a 6-2, 6-2, 6-4 victory over Joao Sousa of Portugal. Murray, who ended a 76-year drought by British men in Grand Slam tournaments with his win at Flushing Meadows last year, didn't allow Sousa a single break point chance.

Standing in the way of a potential second Grand Slam title for Murray is a likely semifinal against No. 2 Roger Federer, who was playing his second-round match Thursday night.