Top seed Rafael Nadal, Swiss Roger Federer, world number four Andy Murray and Victoria Azarenka secured a quarter-finals berth on day eight of the Australian Open.
Rod Laver Arena
Azarenka (Blr)  beat Stephens (US)  6-3 6-2
Serbia’s Azarenka remained on course for a third successive Australian Open by beating Sloane Stephens of the USA in the rematch of last year’s controversial semi-final, when the second-seed took a questionable medical time out to return and seal a win.
Azarenka clinched the first set before going on to maintain dominance in the decider, breaking Stephens in the opening game without dropping a set. The defending champion will meet Agnieszka Radwanska in the last eight
Nadal (Spa)  beat Nishikori (Jpn)  7-6 (7-3) 7-5 7-6 (7-3)
Spaniard Rafael Nadal needed treatment on his racquet hand on his way to seeing off Japan’s Kei Nishikori as well as been called for a second time violation by chair umpire Eva Asderaki at deuce while 4-4 at a critical time in the third set.
The Spaniard did not dispute the 20-second rule in between points at Grand Slams, but took issue with the chair umpire’s handling of it. Nadal faces Grigor Dimitrov in the next round.
“I don’t want to change the rule. I accept that sometimes I was slow. I respect that,” he said. “The negative thing in my opinion is not the warning, but the timing of it. You can choose another moment to do it, not that one.
“She didn’t advise me before the second warning that I was still going slow. It’s a normal thing for the referee to help the player a little bit, and say, ‘Rafa, you are going too slowly’.”
Federer (Swi)  beat Tsonga (Fra)  6-3 7-5 6-4
17-time Grand Slam champion Roger Federer continued in his impressive form to beat France’s Jo-Wilfried Tsonga and advance into the last 8.
The Swiss star broke Tsonga’s service three times, and only had one break point against his own serve. He won 88% of his first-serve points and hit more than twice the number of winners (43) than errors (21), in a clinical performance. The Swiss won 34 of his 41 net points.
He will face Andy Murray, who outlasted France’s Stephane Robert 6-1, 6-2, 6-7 (6-8), 6-2 in four sets.
Cibulkova (Svk)  beat Sharapova (Rus)  3-6 6-4 6-1
Radwanska (Pol)  beat Muguruza (Spa) 6-1 6-3
Alep (Rom)  beat Jankovic (Ser)  6-4 2-6 6-0
Murray (GB)  beat Robert (Fra) 6-1 6-2 6-7 (6-8) 6-2
Margaret Court Arena
Dimitrov (Bul)  beat Bautista-Agut (Spa) 6-3 3-6 6-2 6-4