Daniil Medvedev set up a second-round showdown with home favourite Dominic Thiem at the Vienna Open after defeating Nikoloz Basilashvili in straight sets on Wednesday.
The top seed broke early and late in both sets as he cruised through the opening round a 6-2 6-2 winner.
Next up for Medvedev is a clash with former US Open champion Thiem, who beat him in the semi-finals on the way to triumphing at Flushing Meadows two years ago.
Stefanos Tsitsipas overcame local wildcard Dennis Novak 7-6 (7-2) 6-2 as the Greek ace seeks a third final in as many weeks, having lifted the title in Astana and finished as runner-up to Holger Rune in Stockholm.
Jannik Sinner also advanced in straight sets against Cristian Garin, but Taylor Fritz's ATP Finals hopes suffered a blow after the fourth seed was beaten 6-1 4-6 6-3 by Denis Shapovalov.
Over in Basel, world number one Carlos Alcaraz sailed through to his 11th quarter-final of the season after a commanding 6-4 6-2 win over Botic van de Zandschulp.
Meanwhile, Felix Auger-Aliassime recovered from losing the opening set to deny Marc-Andrea Huesler. The third seed claimed a career-best ninth successive ATP Tour victory, as he looks to complete a hat-trick of titles in as many weeks having recently reigned in Florence and Antwerp.
Stockholm champion Rune built on his recent momentum with a 6-2 7-5 success over Alex de Minaur, but Naples winner Lorenzo Musetti was ousted in a deciding set by Albert Ramos-Vinolas.