British No5 Andy Murray suffered an opening round loss at the hands of world No 76 Facundo Bagnis in Melbourne.
The Argentine beat the Brit 6-3 5-7 6-3 in the opening round of the Melbourne Summer Series.
The competition is often used as a warm up for the Australian Open, which begins on 17 January.
The 34-year-old former world No1’s performance was riddled with errors with Murray even slamming his racket into a bench in frustration during the third set.
The Scot had previously reached the final of an exhibition event in the United Arab Emirates, losing to Andrey Rublev.
Elsewhere, Dan Evans beat Denis Shapovalov 6-4 6-4 in the ATP cup to give Great Britain a 1-0 lead against the Canadians.
Felix Auger Aliassime will play Cameron Norrie in the second singles match.
The Canadian duo will then take on Jamie Murray and Joe Salisbury in the doubles.
Britain are in a tough pool alongside Germany, the US and Canada with just the group winners progressing to the semi-finals.