Dominic Thiem's bid to reach back-to-back Australian Open finals was dashed by Grigor Dimitrov as the US Open champion surprisingly crashed out in the round of 16.

Thiem lost a thrilling final to Novak Djokovic in last year's Melbourne Park decider before breaking through for his maiden grand slam title at Flushing Meadows later in 2020.

But Thiem failed to secure another second-week berth in Melbourne, where the third seed was stunned 6-4 6-4 6-0 by former world number three Dimitrov on Sunday.

Thiem was aiming to reach the Australian Open quarter-finals for the second time and become the second Austrian man to feature in the quarters in Melbourne on multiple occasions after Thomas Muster (1989, 1994 and 1997).

The 27-year-old Thiem was also bidding to reach his ninth slam quarter-final and equal Muster's record for most major last-eight appearances by any Austrian – male or female.

However, Thiem – who rallied from two-sets-to-love down to top Nick Kyrgios in the previous round – was no match for Dimitrov behind closed doors on Rod Laver Arena amid a coronavirus lockdown in Victoria.

Both players hit 25 winners, but Dimitrov only tallied 18 unforced errors to Thiem's 41 following just over two hours on court.

Dimitrov progressed to his fourth Australian Open quarter-final, extending his record for most last-eight appearances at Melbourne Park by a Bulgarian player – man or woman.

An Australian Open semi-finalist in 2017, Dimitrov will now contest his sixth grand slam quarter-final – the 29-year-old is third for most quarter-final appearances by a Bulgarian player, behind Manuela Maleeva (nine) and Katerina Maleeva (seven).