Australian Open Tennis Championship begins in Melbourne today. India's Sania Mirza will begin her campaign against Bulgaria's Tsvetana Pironkova today. The tournament assumes importance for world No. 105 Sania as she needs to improve her ranking to be eligible for a direct entry to the London Olympics. After Somdev Devvarman's withdrawal from the tournament due to injury, Saina is the lone Indian in the singles event. In the doubles, Leander Paes and Mahesh Bhupathi will be contenders with different partners. Bhupathi has paired up with Rohan Bopanna while Paes will partner with Redek Stepanak.