Keys into Melbourne third round, Sinner and Djokovic primedListen to this articleMadison Keys celebrates beating fellow American Ashlyn Krueger at the Australian Open in Melbourne on Thursday. (Photo: AFP)MELBOURNE - An erratic Madison Keys did enough on Thursday to reach the third round in her defence of the Australian Open, where men’s title-holder Jannik Sinner is also in action later. The Italian coasted through round one when his French opponent Hugo Gaston retired with Sinner in a commanding 6-2, 6-1 lead. The 38-year-old, who has won a record 10 titles in Melbourne, looked imperious in a 6-3, 6-2, 6-2 first-round stroll past Spain’s Pedro Martinez. It was his landmark 100th Australian Open victory and a statement of intent as he looks finally to claim a 25th Slam title.