Third-seeded Serena Williams is hard to pick against in Australia

Can Serena Williams win a calendar year Grand Slam? Where’s Rafael Nadal, and when will he be back?

As the 2013 tennis season begins in earnest Sunday (Monday in Melbourne) at the Australian Open, we know that Nadal is not back. He has withdrawn from the first major of the year, as he did from the Olympics and the U.S. Open last year, saying his knee tendinitis has now been trumped by a stomach virus.

Williams, though, seems in the best shape of her career and is still on the high of winning Wimbledon, the Olympics and the U.S. Open.

She is not the defending champion in Melbourne. That honor belongs to top-seeded Victoria Azarenka, but it’s hard for anybody to pick against Williams.

Justin Gimelstob, who will do commentary for the Tennis Channel, says, “It seems like Serena is becoming much more aware of history, and with that is becoming more focused, fit and spends time and energy with her tennis now.”

Lindsay Davenport, a partner with Gimelstob on the Tennis Channel, said it will be difficult for the 31-year-old Williams to sweep the four major events this year. “But it’s just as difficult to pick against her if she stays healthy,” Davenport said of the third-seeded player.

Chris Evert, who will be working for ESPN2, said of Williams and the possibility of a slam: “She’s got the motivation, no doubt about it. If her health stays good, she’s unbeatable. But in this day and age, and we’ve seen it with Nadal, it’s the health. There are no easy matches. Do I think it will happen? I have my doubts because she’s human. But at the moment, she’s a level or two above the opposition.”

On the men’s side, top-seeded and two-time defending champion Novak Djokovic is the favorite. Second-seeded Roger Federer, who is also 31, can suffer in the heat, which has been over 110 degrees the last week. Andy Murray, seeded third, goes to Melbourne now with the belief he can win big tournaments.

“What I did at the end of last year, it meant a lot to my confidence,” said Murray, who won the Olympics and his first Grand Slam tournament, the U.S. Open.

Darren Cahill, the Australian commentator for ESPN2, predicts that Murray will win another major this year, that Nadal will be focused for the French Open and, “Never count Federer out. But you can never bet against Djokovic on a hard surface, so I like his chances here.

“But here in 2013, we might start seeing some of the future. Milos Raonic, Bernard Tomic, Ryan Harrison, among others. Young guys will start coming through.”

John Isner, who would have been the highest-seeded American man, withdrew from the tournament with a bone bruise in his right knee, leaving 22nd-seeded Sam Querrey as the highest-ranked American man.

The tournament will be televised on both ESPN2 and the Tennis Channel beginning Monday.

diane.pucin@latimes.com

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