Thiem started his tournament with a 7-6 (2), 6-2, 6-3 victory over Mikhail Kukushkin, crushed Dominik Koepfer 6-4, 6-0, 6-2 in the second round and rallied from two sets down to oust Nick Kyrgios 4-6, 4-6, 6-3, 6-4, 6-4 in the third round.
Dimitrov has not lost a set en route to the last 16. He began with a 6-4, 6-2, 7-6 (5) victory over former finalist Marin Cilic, dismissed Aussie wild card Alex Bolt 7-6 (1), 6-1, 6-2 in round two and won the first seven games of his third round match against 15th seed Pablo Carreno Busta before the Spaniard was forced to retire.
This is the sixth career meeting between Thiem and Dimitrov with the Bulgarian holding a 3-2 edge. Their last meeting was in the third round of the 2019 Rolex Paris Masters with Dimitrov winning fairly comfortably 6-3, 6-2.
The match will be third on Rod Laver Arena in the day session with the winner facing either 20th seed Felix Auger-Aliassime or Russian qualifier Aslan Karatsev in the quarterfinals.
If you enjoy watching one-handed backhands, this is the match for you as both players have two of the prettiest on tour, which also carry plenty of pace and power on it. Thiem hits a far heavier ball and will want to bully Dimitrov around the court with it.
What's given the Austrian so much trouble is that Dimitrov has a very versatile game. Willing to stay back and rally with his opponent or go on offense and attack, especially at net, which could be an underrated factor in this match.
Dimitrov's athleticism means he'll likely be able to get a lot of balls back, not allowing Thiem to drag him into long rallies while the Austrian will give himself more room to return the 18th seed's serve by standing far behind the baseline.
On paper, this is a match Thiem should win. He's in better form, has done brilliantly in hard court majors the last year (16-1) and has all the tools to even the head-to-head with Dimitrov.
That said, the Bulgarian has played much better of late, is back in the top 20 and has beaten the third seed before. However, Thiem should get by this match, although not without challenges.
Prediction: Dominic Thiem in four sets