Jessica Pegula and Coco Gauff fired early warning shots on Monday at the Australian Open with blistering straight-sets wins as Rafael Nadal prepares to return to the scene of one of his greatest Grand Slam triumphs. 

In-form third seed Pegula blitzed past 161st ranked Romanian Jaqueline Cristian on Margaret Court Arena 6-0, 6-1 in a 59-minute romp to signal her intent.
 
Fellow American Coco Gauff, seeded seven, was equally explosive in racing into the second round with a 6-1, 6-4 thumping of Czech Katerina Siniakova on neighbouring Rod Laver Arena.