• Australian Open, Day Six

Azarenka & Williams through in different styles

Defending-champion Victoria Azarenka and five-time champion Serena Williams both secured their places in the fourth round of the Australian Open on day six, but in contrasting styles.

World No. 1 Azarenka could well have been picking over the bones of a third-round exit at the hands of Jamie Hampton had the American, ranked 63rd in the world, not picked up a back injury in the second set.

Despite the pain, Hampton won the set to level the match and led 2-1 in the third but then conceded five games in a row to give the Belarusian a 6-4 4-6 6-2 victory.

Azarenka's rivals will have noted her mental wobble in the heat of the Rod Laver Arena as she served three double faults in one game when she was seemingly cruising at 5-1 up in the first set.

Hampton, 23, then held her serve and broke again to leave her one service game away from levelling the opening stanza. But with the hard work done she failed to maintain her momentum and lost the set with a double fault of her own.

Azarenka had to play catch-up throughout the second and defended two set points when she was 5-3 down. But in the same game Hampton's lower back started to give her problems and she called a medical time-out. On her return, and although visibly still in pain, she served out to level at 1-1 before taking the lead in the third, yet Azarenka overran her to gratefully reach the next round.

"All credit to her, she has a great future in front of her, she has great potential," Azarenka said. "She took a medical time-out but she was ripping winners all over. I thought 'can I have a back problem?!' I was feeling great but missing every shot."

Serena Williams' only blemish in an otherwise dominating performance was going 3-0 down at the beginning of the second set against Japan's Ayumi Morita. But the third seed responded with six straight games to win the match.

Williams displayed no signs of the ankle injury picked up in the first round, which hampered her movement in Thursday's second-round meeting with Garbine Muguruza.

The 31-year-old is chasing a third consecutive major title and showed again how strong she is on her serve by clocking a 128 mph [207 kph] delivery for the second time in the tournament.

"I tried to hit it really hard," Williams said. "I hit 207 the other day and I thought it was luck but I did it again and I was like whew! I'm going to try to go for 210. We'll see."

Former quarter-finalist Maria Kirilenko beat Belgium's Yanina Wickmayer 7-6(4) 6-3 in a little under two hours to set up a clash with Williams on Monday.

Meanwhile Caroline Wozniacki did just enough to see off Lesia Tsurenko 6-4 6-3 in a match that looked comfortable on paper but saw the Dane lose five service games and hit only five winners. The tenth seed will now play Russian Svetlana Kuznetsova, also on Monday.

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