Top seed Stefanos Tsitsipas of Greece saved three set points in the first set to take down Bulgaria's Grigor Dimitrov 7-6 (6), 6-4 in a first-round match Tuesday at the Erste Bank Open in Vienna, Austria.
Tsitsipas withstood 10 aces from Dmitrov and saved all four break points he faced in the one-hour, 42-minute win. He next faces Frances Tiafoe, who defeated Tsitsipas earlier this year in straight sets at Wimbledon. Tiafoe reached the second round with a 6-4, 6-4 win over Serbian Dusan Lajovic.
Other first-round winners included No. 2 seed Alexander Zverev of Germany, No. 4 Casper Ruud of Norway, No. 6 Felix Auger-Aliassime of Canada, Cameron Norrie of Great Britain and Austria's Dennis Novak.
St. Petersburg Open
Fifth-seeded Taylor Fritz defeated Finnish qualifier Emil Ruusuvuori 6-1, 6-4 in 68 minutes in the opening round in St. Petersburg, Russia.
That sets up a second-round clash with countryman Tommy Paul, a 6-3, 6-2 winner against Spain's Pedro Martinez. The two friends have never faced one another in an ATP Tour-level match.
Others advancing included their fellow American Mackenzie McDonald, U.S. Open quarterfinalist Botic van de Zandschulp of the Netherlands, Ilya Ivashka of Belarus, Pablo Andujar-Alba of Spain and John Millman of Australia.
-Field Level Media