MELBOURNE -- Check out the key matches to watch for Sunday's action in Melbourne.
Popcorn match: Andy Murray vs. Grigor Dimitrov
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
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.