Below are all the scores along with a recap of the highs and lows from Day 8 at the Australian Open.
|Rafael Nadal (1) def. Kei Nishikori (16)||7-6, 7-5, 7-6|
|Roger Federer (6) def. Jo-Wilfried Tsonga (10)||6-3, 7-5, 6-4|
|Andy Murray (4) def. Stephane Robert||6-1, 6-2, 6-7, 6-2|
|Grigor Dimitrov (22) def. Roberto Bautista-Agut||6-3, 3-6, 6-2, 6-4|
|Dominika Cibulkova (20) def. Maria Sharapova (3)||3-6, 6-4, 6-1|
|Victoria Azarenka (2) def. Sloane Stephens (13)||6-3, 6-2|
|Agnieszka Radwanska (5) def. Garbine Muguruza||6-1, 6-3|
|Simona Halep (11) def. Jelena Jankovic (8)||6-4, 2-6, 6-0|
Big Guns Make Progress
Murray battled his way into the quarterfinals after besting Stephane Robert in four sets.
The Brit appeared to be cruising to another straight-sets victory when he won the opening two sets 6-1, 6-2, but his French opponent struck back to claim the third in a tiebreaker.
Murray smashed a racket in frustration, which can be viewed in this video from the tournament's official Twitter account:
He regained composure to finish the job and won the fourth set 6-2 to set up a last-eight meeting with four-time champion Federer, who beat Jo-Wilfried Tsonga in straight sets.
Federer was in imperious form as he dispatched Tsonga 6-3, 7-5, 6-4 to send out a statement of intent as he attempts to claim an 18th Grand Slam.
ESPN Tennis noted how easy he made his victory look:
Nadal may await the winner of Murray vs. Federer after he too made progress, topping 16th-seed Kei Nishikori 7-6, 7-5, 7-6 in a hard-fought match that saw the Spaniard overcome a nasty blister and a warning for time violations.
Nadal will now face Grigor Dimitrov, the lowest seed left in the tournament. Elsewhere, Tomas Berdych will play David Ferrer, and Stanislas Wawrinka will take on Novak Djokovic.
Shock for Sharapova
In the women's singles, third-seed Sharapova departed the tournament after being beaten in three sets by Dominika Cibulkova.
Sharapova, winner of the Australian Open in 2008, needed a medical timeout before the final set and finished with 45 unforced errors, including seven double faults in the final set, before eventually losing 3-6, 6-4, 6-1.
Eighth-seed Jankovic is also out, falling to Simona Halep 4-6, 6-2, 0-6.
Both losses will serve as a boost to holder Azarenka, who cruised past Sloane Stephens 6-3, 6-2. Following that win, Eurosport quoted her saying:
I just love playing here. It feels so cosy. It feels like I'm in my living room, on my couch.
I can have some chips and salsa - that's how it feels.
Fifth-seed Agnieszka Radwanska lies in wait for Azarenka in the quarterfinals, while Cibulkova's reward is a tie against Halep.
In the other games, Li Na will take on Flavia Pennetta, and Ana Ivanovic faces Eugenie Bouchard.
Predicting the Quarterfinals
Murray will face his toughest test of the tournament in the semifinals against an in-form and hungry Federer determined to win another Grand Slam.
The game will likely be decided by whoever brings his best serve with him, with Murray winning 69 percent of points with his first serve against Robert, and Federer going better to hit 79 percent against Tsonga.
If the Scot is able to hold his nerve and see off the veteran to extend his 11-9 career advantage, then it would play him into form in time for a potential semifinal showdown with Nadal.
Nadal and Djokovic appear to have straightforward routes to the last four against the No. 22 and No. 8 seeds, respectively, but No. 3 seed David Ferrer can expect a real test to get past Berdych in the other quarterfinal after taking almost three hours to see off Florian Mayer, per AusOpen.com.
If Azarenka, who has not dropped a single set so far, is able to take care of Radwanska in the pick of the quarterfinals in the women's singles, then she will be viewed as a big favourite to hold on to her crown.
Her main threat is China's Li Na, the fourth seed, who should progress against 28th seed Flavia Pennetta.
As many as five of the last eight are eligible to fall into the outsider category, even at this late stage of the tournament, and the field is open for Azarenka after the exits of Serena Williams and Sharapova.