Australian Open 2014: day eight – in pictures

The eight-and-a-half hours that she had already spent on court during the first week seemed to take it's toll on Maria Sharapova as she took on Dominika Cibulkova. Despite this she took the first set 6-3 Photograph: Ryan Pierse/Getty Images

Cibulkova started to dominate and raced to a 5-0 lead before a wobble gave Sharapova the chance to take the next four games. However the wobble was rectified and the No20 seed took the second set 6-4 Photograph: Matt King/Getty Images

Cibulkova raced to a 5-1 lead in the deciding set and then Sharapova served three double faults in the seventh game to hand Cibulkova match point. Sharapova survived that one, only to shove a regulation forehand into the tramlines then hit long and the No3 seed was out Photograph: Mark Dadswell/EPA

Sloane Stephens was up against Victoria Azarenka in a repeat of last year's semi-final. The defending champion Azarenka took to the first set 6-3 Photograph: Clive Brunskill/Getty Images

She then put away the American with ease, taking the second set 6-2 Photograph: DAVID CROSLING/EPA

Kei Nishikori took the No1 seed Rafael Nadal to a tie-break in the opening set of their match but the Spaniard edged it to take the first set Photograph: Mast Irham/EPA

Nadal was pushed hard again before he took the second set Photograph: David Gray/Reuters

The third set also went to tie-break which a determined Nadal won to take the match 7-6 (7-3), 7-5, 7-6 (7-3) Photograph: Ryan Pierse/Getty Images

Roger Federer started strongly in his match against Jo-Wilfried Tsonga, taking the first set 6-3 Photograph: Eugene Hoshiko/AP

There was frustration for Tsonga in a ding-dong of a second set which Federer eventually took 7-5 Photograph: Petar Kujundzic/Reuters

Federer's imperious form continues in the third set which he won 6-4 Photograph: Aaron Favila/AP

Agnieszka Radwanska had little trouble defeating Garbine Muguruza in straight sets 6-1, 6-3 Photograph: Mast Irham/EPA

Simona Halep started strongly in her match against Jelena Jankovic and took the first set 6-4 Photograph: William West/AFP/Getty Images

Jankovic fought back and got back on level terms when she won the second set 6-2 Photograph: Rick Rycroft/AP

The tide of the match turned again in the deciding set which Halep took without losing a game to make it through to the last eight Photograph: Jason Reed/Reuters

Andy Murray seemed in a hurry in his match against Stéphane Robert as he raced through the first set which he took 6-1 Photograph: Jason Reed/Reuters

He continued apace to take the second set 6-2 Photograph: Brandon Malone/Reuters

It was at this point that Murray faced resistance from Robert as the Frenchman took the third set to a tie-break Photograph: Clive Brunskill/Getty Images

After squandering four match points at the end of the third set and consequently losing the set 7-6 (8-6), Murray took out his frustrations Photograph: Brandon Malone/Reuters

Normal service was resumed in the fourth set which Murray took 6-2, and the win sees him through to the quarter-finals Photograph: Mal Fairclough/AFP/Getty Images

Grigor Dimitrov, became the first Bulgarian male to reach a grand slam quarter-final after beating Roberto Bautista Agut 6-3, 3-6, 6-2, 6-4 Photograph: Mal Fairclough/AFP/Getty Images