Australian Open 2014: Serena Williams into round four

Top seed Serena Williams continued her serene progress at the Australian Open as she eased into the fourth round on another day of extreme Melbourne heat.

The American, 32, controlled her contest against 31st seed Daniela Hantuchova to win 6-3 6-3, a tournament-record 61st singles victory.

Five-time champion Williams has yet to drop a set in this year's competition.

The temperature continued to be an issue for players, a day after matches were suspended because of 43.3C heat.

Rod Laver Arena

S Williams (US) [1] beat Hantuchova (Svk) [31] 6-3 6-3

Williams was not quite at her best and appeared to be struggling with the heat, though she still proved too strong for Hantuchova.

The world number one raced into a 5-3 lead but had to save two break points to hold serve before clinching the first set.

Williams broke early in the second set but her opponent was in battling mood and responded to level at 3-3.

Hantuchova's hopes were short-lived, however, as Williams seized the initiative in the Slovakian's next service game and served out for the victory, sealing it with a powerful forehand winner on her fourth match point.

"It was a tough match," said Williams. "Daniela is a great opponent so I'm really happy to come out with the win. It was hot but you have to play, you have to be ready and prepare yourself mentally. I'm excited to get through."

Chardy (Fra) [29] v Ferrer (Spa) (3]

Zheng (Chn) v Dellacqua (Aus)

Stosur (Aus) [17] v Ivanovic (Ser) [14]

Istomin (Uzb) v Djokovic (Ser) [2]

Hisense Arena

Kerber (Ger) [9] beat Riske (US) 6-3 6-4

Li (Chn) [4] v Safarova (Cze) [26]

Berdych (Cze) [7] v Dzumhur (Bih)

Robredo (Spa) [17] v Gasquet (Fra) [9]

Margaret Court Arena

Pennetta (Ita) [28] beat Barthel (Ger) 6-1 7-5

Anderson (SA) [19] v R-Vasselin (Fra)

Fognini (Ita) [15] v Querrey (US)