Grind of tour takes toll on walking wounded MELBOURNE (Reuters) - The unrelenting grind of the professional tennis tour moves back into high gear on Monday with an Australian Open shorn of Rafa Nadal and several players carrying niggling injuries into the draw. Nadal, who battled Novak Djokovic for almost six hours before the Serb finally sealed the title last year, withdrew last month because a stomach virus was hampering his recovery from a long term injury in his creaking knees. World number 14 John Isner joined him as absent last week when he withdrew from the Sydney International tournament due to a knee injury, while several other men's' seeds withdrew from warm-up tournaments to manage their injuries. Japan's Kei Nishikori, who made the quarter-finals at Melbourne Park last year, withdrew from the invitational Kooyong tournament with a knee injury, Juan Monaco did likewise with a hand injury, while world number eight Jo-Wilfried Tsonga withdrew from Sydney with a hamstring strain. Tsonga, a finalist at Melbourne Park in 2008 played down any lingering issues with his injury, declaring he was good to go, while Japan Open champion Nishikori said on Sunday he was at about "90 percent" having practiced at Kooyong on Friday and Saturday. "I played (at) Kooyong two days ago, yesterday and it was fine," Nishikori said of his recovery. So I played three set and nothing happened yesterday, so should be okay for tomorrow. In a strange twist, the women's side of the draw at last year's opening grand slam resembled a list of the walking wounded, though only the top-two seeds were effected this year, or least were letting on. Women's champion Victoria Azarenka pulled out of Brisbane with an infected toe, just 30 minutes before she played Serena Williams in their semi-final, though she said she did not regret the decision and was ready to play in Melbourne. "I don't feel any pain when I play," Azarenka said of the toe that got infected from a pedicure. I still have to tape it, but there is no problem. I think I did a very good choice (to withdraw in Brisbane). I'm feeling good right now. So the only thing that I feel is that I made the right decision. World number two Maria Sharapova also had been under an injury cloud heading into the tournament with pain around her collarbone that badly affected her preparations and had no competitive matches under her belt. Because of her injury, the Russian was one of the first to arrive in Melbourne and instead practiced against several promising Australian juniors and played former top-five player Daniela Hantuchova on Saturday. "I'd rather be going onto the court knowing that I'm healthy," Sharapova said after her practice match against Hantuchova. I might be a little bit rusty, but I'll work my way through it. I'm experienced enough to know the adjustments I have to make in those types of circumstances.