Melbourne:Leander Paes and Martina Navratilova will be in action in the mixed doubles semi-final against the unseeded pair of Jonathan Erlich of Israel and Liezel Huber of South Africa. Paes and Navratilova are the defending champions and had created history when they won the Wimbledon mixed doubles title last year. Martina is the oldest ever to win a Grand Slam title at 46. She is also the only platyer to win all three titles - women's singles, doubles and mixed doubles at all four Grand Slam tournaments. This is Leander's first tournament after being treated for a brain abscess.