World number 175 Chris O'Connell scores incredible Australian Open upset with victory over 13th seed Diego Schwartzman

Local wildcard Chris O'Connell has sent 13th seed Diego Schwartzman crashing out of the Australian Open to advance to the third round at a grand slam for the first time.

After claiming a marathon opening set in a tiebreak, the late-blooming O'Connell continued to play the big points better against the Argentinian counter-puncher.

O'Connell wrapped up the upset victory 7-6 (8-6), 6-4, 6-4 in three hours and seven minutes to set up a round-of-32 clash against American Maxime Cressy.

As was the case with O'Connell, it will be the first time in the third round at any major for Cressy, who advanced by beating Czech qualifier Tomas Machac 6-1, 3-6, 6-1, 7-6 (7-5).

Schwartzman had reached the third round at Melbourne Park in each of the past four years and had never before lost at a grand slam to a player ranked as low as O'Connell, whose world ranking is 175th.

But the Australian underdog was roared home to victory by a raucous home crowd on Court 3.

The 27-year-old had recorded just two victories at grand slams in his career prior to this tournament.

He'll face American Maxime Cressy in the third round. 

Plenty of other Aussie hopefuls are in action on day three, with Madison Inglis taking on American Hailey Baptiste before superstars Alex di Minaur and Nick Kyrgios take centre stage later in the evening. 

Earlier, Sam Stosur's singles career came to an end, with the veteran going down to Anastasia Pavlyuchenkova 6-2, 6-2.

AAP/ABC