Rod Laver Arena
 Simona Halep (ROU #3) vs.  Ekaterina Makarova (RUS #11)
Head-to-head: Halep leads 1-0
In last year's quarterfinals, Simona Halep struggled under the spotlight of Rod Laver Arena. In her first match on Melbourne's main arena and in the last eight of a major, Halep was blown away by an on-song Dominika Cibulkova - something she does not expect to happen this time around.
On the other side of the net this year is another mercurial talent: Ekaterina Makarova. But a year older and wiser - and on a nine-match winning streak - Halep is ready for battle.
"I had good matches here in the first week, so I'm really happy that I'm in the second week now like last year," Halep said. "I've started to play my best tennis in Grand Slams, which is important to me. I really have more confidence now to play the quarterfinals."
 Maria Sharapova (RUS #2) vs.  Eugenie Bouchard (CAN #7)
Head-to-head: Sharapova leads 3-0
No sooner had she announced herself to the tennis world with a run to the semifinals at last year's Australian Open, than Eugenie Bouchard was hastily being christened as Maria Sharapova's heir apparent.
A few months later, Bouchard came face to face with the player that inspired her to first pick up a racquet, losing a tight three-setter to Sharapova. However, the bitter taste of defeat only fuelled the Canadian's appetite to perfect an already impressive game, and go one better on Tuesday afternoon.
"I felt like I was close with her in Paris," Bouchard said. "Neither of us played our best that day, so I remember that, and I remember I had chances and stuff. I just remember a tough match. I was pretty disappointed after, so that's motivation for the next time."
Read more details and stats about Tuesday's match-ups in our Match Notes.