Clive Brunskill/Getty Images
By Courtney Nguyen
January 24, 2015

MELBOURNE -- Check out the key matches to watch for Sunday's action in Melbourne.

Popcorn match: Andy Murray vs. Grigor Dimitrov

Murray has cruised through the early rounds without losing a set. Now comes his first test of the tournament in Dimitrov (second night match, Rod Laver Arena). Murray leads the head-to-head 4-2 but in their only match at a Slam, Dimitrov ousted Murray from Wimbledon last year in straight sets. Dimitrov, he needed five sets to get past Marcos Baghdatis in the last round, though given his tough training regime under coach Roger Rasheed you have to expect he's recovered well. 
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A win for Murray and he'll extend his streak of Slam quarterfinal appearances to 16. Either way, this is a big statement match for Murray. His incredibly difficult draw softened just slightly with Roger Federer's shocking loss in the third round. Now the winner of this match will play either Nick Kyrgios or Andreas Seppi.

Rafael Nadal faces No. 14 Kevin Anderson

The outcome of Sunday's match depends on Nadal (third match, Rod Laver Arena). He struggled through stomach cramps and fatigue to narrowly avoid the upset against Tim Smyczek in the second round, but bounced back to lose just six games to Dudi Sela on Friday night. 

Anderson will need a big serving day to keep the scoreboard pressure on Nadal. He's looking to become the first South African to make the quarterfinals of a Slam since Wayne Ferreira in 2003. 

Nick Kyrgios guns for his second Slam quarterfinal

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What does an Aussie No. 1 have to do to get on Rod Laver Arena? Kyrgios will have a packed Hisense Arena -- the tournament's No. 3 court -- when he takes on Federer's vanquisher Andreas Seppi (6:15 p.m. local time). The two have played just once, at last year's U.S. Open, and Kyrgios won 6-4, 7-6, 6-4. The 19-year-old continues to serve huge despite nursing a back problem. Should he win, he could become the first Australian man to make the quarterfinals in Melbourne since Lleyton Hewitt in 2005. He would also be the youngest man to make the Australian Open quarterfinals since 1990.

Bernard Tomic tries to solve Tomas Berdych

Berdych has ended Tomic's last two Wimbledon campaigns, winning in four sets each time. Tomic is on a nine-match losing streak to Top 10 opposition. 

Simona Halep looks for her first win over Yanina Wickmayer

Wickmayer has never beaten a Top 5 opponent. Halep has never won a set off Wickmayer, who comes into the tournament ranked No. 80. Something's gotta give. The two haven't played each other since Halep's meteoric rise. They last faced off in Hobart in 2012, where Wickmayer won 6-4, 6-0. The Belgian has played a lot of tennis to make the fourth round. All three of her matches have gone the distance, chalking up wins over No. 23 Anastasia Pavlyuchenkova and No. 14 Sara Errani. Despite the head-to-head record, expect Halep to cruise here.

More matches to watch

Maria Sharapova [2] vs. Peng Shuai [21]: The Russian leads the head-to-head 4-1, with Peng's sole win coming in 2009. Aside from that second round blip against No. 150 Alexandra Panova, Sharapova has looked sharp.

Eagle (-2)
Birdie (-1)
Bogey (+1)
Double Bogey (+2)