Aussie wildcard Chris O’Connell scored the biggest upset so far at this year’s Australian Open, defeating No. 13 seed Diego Schwartzman 7-6 (8-6), 6-4, 6-4 in three hours and seven minutes.

Cheered on by a vociferous local crowd, O’Connell won the first set on a tiebreak and from there pushed on to take the match in straight sets.

O’Connell found himself down 4-5 in the tiebreak, but reeled off four of the next five points to win the set.

Chris O’Connell celebrates his second round victory over Diego Schwartzman. Photo: Roger Parker International Sports Fotos Ltd

The second set saw both players trading shots before O’Connell broke to go 5-4 up, holding serve totake it 6-4.

The Aussie then created three break point chances early in the third but Schwartzman fought back to stay in the match, before O’Connell broke again at 4-4 to stay ahead and serve out the match.

He will face American Maxime Cressy in the round of 32.