Top players almost always say that the first round of a major is a hard one. The player is trying to get used to the courts, shake off nerves, and establish a rhythm to take her through the first week. Some of the tour's elite "play their way into" the deep part of the draw, improving as time passes and the opponents become more difficult.
This year, in Australia, a few really good players won't have the luxury of using the first round as a way of warming up for the rest of the tournament; rather, they will have their hands full:
Caroline Wozniacki vs. Gisela Dulko: Dulko, like so many players, has good service days and bad service days. A deceptively hard hitter for someone her size, the world number 1 doubles player--when she's having a good service day--can beat just about anyone. If Dulko's serve is off, Wozniacki will wear her down without too much effort. But if it's on, the top seed will have to work.
Yanina Wickmayer (21) vs. Jarmila Groth: Groth is in the Hobart final, and she made a very good showing in Brisbane, taking out Sam Stosur. Wickmayer has a lot of endurance, but Groth's serve can be a mighty force. If any top first round match is an accident waiting to happen, this would be it.
Kimiko Date Krumm vs. Agnieszka Radwanska (12): Radwanska is just returning to the tour after surgery and rehab, and she probably can't imagine anything worse than facing Date Krumm in the first round.
Maria Jose Martinez Sanchez (26) vs. Greta Arn: Martinez Sanchez is a clever competitor, and has one of the better serves on the tour, but she can't always muster it when she needs it. Arn just won Auckland, so her confidence is likely to be at a high level.
Dinara Safina vs. Kim Clijsters (3): This is what it has come to--multiple title-winner and French Open and Australian Open finalist Safina has to deal with 3rd seed Clijsters, one of the players who is favored to win the whole thing. Safina, who is struggling to regain her form after suffering repeated problems with her back, is likely to give Clijsters a good match. It's the first round, and Safina isn't expected to win, so there shouldn't be too much pressure.
There are a few potential qualifiers who could also make trouble. For example, if Sabina Lisicki qualifies (she won her first qualifying round), she could be a tough first round opponent. No one will have to worry about Kristina Mladenovic, though. She was defeated by Heather Watson in the first round of qualifying.