MELBOURNE, Australia -- Rafael Nadal, Maria Sharapova, Roger Federer, Andy Murray and Juan Martin del Potro are all up on Day 4 of the Australian Open, where once again the thermometers will read in the triple digits for most of the day.
Sharapova opens play on Rod Laver Arena against No. 44 Karin Knapp. Murray anchors the night session against a qualifier, Vincent Millot, ranked No. 267. Both should get through easily.
Rafael Nadal  vs. Thanasi Kokkinakis (third match on Rod Laver Arena): Because of Bernard Tomic's retirement in the first round, Nadal lost the opportunity to play a full match and adjust to the conditions on Rod Laver Arena. It shouldn't be a problem when he takes on another young Aussie in Kokkinakis (they call him "The Kokk" down here), a 17-year-old wild card. But it's something to consider.
Roger Federer  vs. Blaz Kavcic (fourth match, Hisense Arena): Last year at the U.S. Open, Federer played on Louis Armstrong Stadium (not Arthur Ashe) for the first time in seven years, and he lost to Tommy Robredo. Now, barring a withdrawal, Federer will make the hike out to the Australian Open's secondary show court for the first time since 2004. Kavcic shouldn't give him any trouble, but it'll be surreal watching Federer take the court. Hisense has a completely different feel.
Sloane Stephens  vs. Ajla Tomljanovic (second match, Margaret Court Arena): Perhaps Stephens' nerves have settled down after her first match, in which she came back from 1-5 down to beat Yaroslava Shvedova in straight sets. She knows Tomljanovic from their junior days when they trained at Chris Evert's academy together in Florida. "I just remember she hit really hard," said.
Gael Monfils  vs. Jack Sock (fourth match, Margaret Court Arena): Stephens' good friend Sock has a tall task against Monfils, who knocked out Ryan Harrison in straight sets in the first round. It was a surprisingly straightforward win for Monfils and just the type he needs to get through these early rounds. It should be interesting to see Sock try to hit through Monfils. The Frenchman really gets to show off his creativity in these kind of matches.
Gilles Simon  vs. Marin Cilic (third match, Show Court 2): Can Simon even walk after saving seven match points and beating Daniel Brands 6-7 (4), 6-4, 3-6, 6-3, 16-14 in a first-round match that lasted four hours and 32 minutes? On crutches just a few days ago because of an ankle injury, Simon won't get a breather against a former Australian Open semifinalist in Cilic, who is playing his first major since returning from an anti-doping suspension.
Andreas Seppi  vs. Donald Young (first match, Show Court 3): Seppi defeated Lleyton Hewitt in five sets in the first round. Young made the second round thanks to a retirement from Robin Haase after the first game of the fourth set, so he'll be fresher than Seppi. I like the 24-year-old American's chances for the upset.
Alize Cornet  vs. Camila Giorgi (first match, Margaret Court Arena): Take Cornet's on-court drama and Giorgi's off-court drama and you have a weirdly compelling match. Upset special: Lu Yen-Hsun vs. Grigor Dimitrov  (third match, Court 6): Dimitrov has never made it past the second round at the Australian Open and he's been to the third round of a Grand Slam only once, at the 2013 French Open. On the other hand, the 53rd-ranked Lu is on a roll in January, beating David Ferrer in the Auckland semifinals last week. This will be a big test for Dimitrov's physicality, with temperatures expected to soar once again.