The biggest obstacle to Serena Williams' progress at this year's Australian Open has, so far, been herself.

The American, seeking a sixth title in Melbourne, went into today's second-round clash with Spanish teenager Garbine Muguruza nursing a twisted right ankle, suffered in a heavy fall during her whitewash of Edina Gallovits-Hall on Tuesday.

And although 19-year-old Muguruza did not have the weapons to really test Williams' movement today, the third seed managed do herself further damage, hitting herself in the face with her racket midway through the first set.

It was hard to tell whether the constant dabbing of her mouth was caused by pain or embarrassment but it mattered little as Williams came through 6-2 6-0.

"I bust my lip wide open," she explained. "One day I twist my ankle, today I hit myself in the face - I don't know what's going to happen on Saturday.

"I'm hoping maybe I'll just hit some winners."

The lip will heal pretty quickly. Of greater concern to Williams was her ankle, but she claimed it was feeling surprisingly good post-match.

"I didn't feel anything today," she added. "Obviously when you go out to play you're heavy on adrenaline and you're really pumped up.

"Usually I feel injuries after the match but so far, so good.

"I feel pretty much better than I ever dreamed of expecting to feel."

Williams, who plays Ayumi Morita next, followed top seed Victoria Azarenka on to Rod Laver Arena - the Belarusian taking 55 minutes to see off Eleni Daniilidou 6-1 6-0.

Having struggled to put away her first-round opponent Monica Niculescu on Tuesday, Azarenka was in no mood to offer any freebies to Greek Daniilidou, who won their only previous meeting in 2008.

Azarenka has developed into one of the major forces in the women's game since then and the gulf in class was evident from the outset.

Daniilidou did not get on the board until the sixth game and her broad grin and raised finger suggested she was already accepting of her fate.

Azarenka won the first set in 24 minutes and although the second was marginally more competitive, despite the scoreline, there was only ever going to be one winner as the defending champion advanced to a clash with American Jamie Hampton.

"Today was much better," said Azarenka.

"I am back in competitive mode, 100%, and was really focused. That was the best part of the game for me."

Azarenka, Williams and second seed Maria Sharapova have made it into round three for a combined loss of eight games. But the world number one dismissed suggestions the increasing amount of lop-sided matches in the early rounds of the women's draw was damaging for the game.

She added: "I think it's really competitive, the scoreline doesn't tell the whole story about the match and to win matches 6-0 6-0 requires a lot of discipline, a lot of focus.

"I can only speak for myself but it seems like everybody is in great form so it's going to be very interesting."

Former world number one Caroline Wozniacki moved quietly into round three with a 6-1 6-4 defeat of 16-year-old Croatian Donna Vekic.

Vekic has been tipped as a star of the future in the women's game but she was too wild to trouble the Dane today.

At the other end of the age spectrum, Kimiko Date-Krumm showed no sign of slowing down, the 42-year-old moving through with a 6-2 7-5 win over Shahar Peer.

Date-Krumm's win over Nadia Petrova on Tuesday made her the oldest woman to ever win a singles match in the tournament's history and she again impressed despite the brutally hot conditions.

Asked for the reasons behind her longevity, the Japanese said: "Nothing special. Just use the energy for tennis and that's it. Sleep a lot, drink water a lot."

Fourteenth seed Maria Kirilenko and number 20 Yanina Wickmayer set up a third-round clash with wins on day four.

Kirilenko ousted Peng Shuai 7-5 6-2 and Wickmayer won a tighter contest against Jana Cepelova 7-6 (8/6) 7-5.