Stefanos Tsitsipas blasted into a fourth Australian Open semi-final on Tuesday and a showdown with Karen Khachanov as he zeroes in on a maiden Grand Slam title. The Greek third seed proved too powerful for unseeded Czech Jiri Lehecka on Rod Laver Arena, storming home 6-3, 7-6 (7/2), 6-4. He will face the Russian 18th seed