World number 56 Makerova had slayed five-times champion Serena Williams in the fourth round with venomous backhands and dogged determination, but she was let down by an insipid serve against Sharapova, who ran out an easy 6-2 6-3 winner.

Briton Andy Murray never looked in any danger of succumbing to another seismic shock at Melbourne Park, swatting aside Japan's Nishikori 6-3 6-3 6-1 on Rod Laver Arena.               

Novak Djokovic, who kickstarted a sublime 2011 season by beating Murray in last year's Australian Open final, faces fifth-ranked Spaniard David Ferrer in the evening session.           

Czech Petra Kvitova bounced Italian surprise package Sara Errani out of the quarter-finals 6-4 6-4 in the day's opening match, enjoying the early overcast conditions that gave way to the more familiar strong sunshine later in the day.          

The diminutive Errani would not have looked out of place in a ball-kids' uniform but measured up well against six-footer Kvitova, refusing to buckle under the Czech's brutal backhands. 

Kvitova worked hard to take the first set but the world number two found herself trailing 4-1 in the second as Errani upped the tempo and started to let loose on the forehand.              

Kvitova fought back to take the next five games but was her own worst enemy at times and looked exasperated after committing 44 unforced errors.    

"At the beginning I was a little nervous because I knew everybody expected it to be an easy match," the 21-year-old Wimbledon champion told reporters.              

"Of course you have a little pressure on your back because you have a grand slam and everybody is expecting that you win all your matches when you play. But it's not really easy."             

GRUNTING DEBATE            

Kvitova is one of three women in with a chance to take over the world number one ranking from Caroline Wozniacki, who was knocked out by Kim Clijsters on Tuesday. The other two are Victoria Azarenka and Maria Sharapova, who Kvitova beat in last year's Wimbledon final.    

Sharapova will get the chance to avenge that defeat after seeing off Makarova in straight sets.               

The Melbourne Park crowd have given fellow primal screamer Victoria Azarenka a hard time throughout the tournament but they were more forgiving of the Sharapova shrieks, which assaulted eardrums anywhere in the vicinity of Rod Laver Arena.

Sharapova, who won the last of her three grand slams at Melbourne Park in 2008, shrugged off the debate about her "grunting" and said she had no plans to tone it down.    

"I've been the same over the course of my career. No one important enough has told me to change or do something different," she added.    

Japan's Nishikori also made a lot of noise in Melbourne with his stunning fourth-round win over Frenchman Tsonga, but his excellent run came to a halt at the hands of a ruthless Murray.  

Nishikori, the first Japanese man through to the last eight in Melbourne for 80 years, was cheered on by kimono-clad fans at Rod Laver Arena but bowed out after a two-hour 12-minute thrashing.             

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