MELBOURNE, Australia -- Here's a look at some notable matches on Day 4 of the Australian Open:Gilles Simon (6) vs. Chris Guccione: One by one, the Aussies are dropping like flies. Darling Casey Dellacqua choked away an upset win over a similarly nervous Daniela Hantuchova on Monday, feisty baseliner Lleyton Hewitt failed to cope with the power of explosive Chilean Fernando Gonzalez on Tuesday, and unpredictable lefty Gilles Muller of Luxembourg ended the short, uplifting sojourn of 16-year-old wonder kid Bernard Tomic.
On the men's side, anyway -- Samantha Stosur meets German Sabine Lisicki in an intriguing women's battle Thursday -- Guccione is the last fella standing. Mark Edmondson's name is often bandied about these parts, since the bald, lovely-mustached right-hander was the last Aussie man to win the title (in 1976), and he'll probably hold that distinction heading into 2010. But Guccione, a coachless behemoth, might give the affable Simon a few headaches.
Though positioned outside the top 100, the 6-foot-7 lefty nevertheless possesses a huge serve. Guccione upset hot and cold Czech Tomas Berdych at the Sydney International just last week and reached the final of the same event last year. He's competing in his hometown and eliminated Frenchman Nicolas Devilder in the first round.
"I'm going to go into the match and be confident out there and try to get off to a good start, hopefully serve well," Guccione said. "Serve is going to be important against him, because he's a great returner. I think I'm going to need some free points out there, and hopefully I can get on to a few of his service games here and there."
Simon became a household name -- at least in Roger Federer's domain -- by topping the Swiss player twice in 2008. Armed with a game similar to blossoming Scot Andy Murray, Simon also topped Rafael Nadal on the Spaniard's turf at the Madrid Masters to confirm his breakthrough.
So far, mediocrity has followed. Simon struggled at the team Hopman Cup in Perth, then exited in his opener in Sydney. Not the best of omens as the 24-year-old seeks a maiden appearance in the second week of a major.
Prediction: Simon in five.
Venus Williams (6) vs. Carla Suarez Navarro: Blessed with a picturesque one-handed backhand, Suarez Navarro rose more than 100 spots in the rankings last year, finishing at No. 50. Much of the escalation resulted from a quarterfinal showing at the French Open, which was all the more impressive given that the 20-year-old had to qualify. Williams' vulnerability in early rounds of Grand Slams has been exposed in the past. Then again, Suarez Navarro finds it hard to win on surfaces other than dirt.
Prediction: Williams in two.
Ivo Karlovic (25) vs. Mario Ancic: Will the 6-10 Karlovic, for all his serving prowess, ever reach a Grand Slam quarterfinal? Will Ancic, no shorty at 6-5, ever regain the momentum wiped away by bouts of mono? A win for either Croat -- they were Davis Cup teammates -- would help. Don't expect many long points, which should suit both well in the heat. Another question: Who will the Croatian fans be rooting for?
Prediction: Karlovic in four.
Ravi Ubha is a frequent contributor to ESPN.com.