Top seed Alexander Zverev needed three sets to overcome a stubborn Viktor Troicki and progress to the second round of the Vienna Open on Monday.
The German won 6-3 4-6 6-4 in one hour and 44 minutes at the ATP 500 event on indoor hard courts at the Wiener Stadthalle.
Having battled back to level the match at 1-1, Serbian Troicki gave up a double break to start the decisive third set on the back foot.
And although Zverev handed one of those breaks straight back, the world number five did not falter after that moment, winning it on his first match point.
Philipp Kohlschreiber caused an upset when he ousted fifth seed John Isner 7-6 (8-6) 6-4, and qualifier Pierre-Hugues Herbert also claimed a notable scalp.
The Frenchman registered a 7-6 (7-4) 7-5 victory over Bernard Tomic, who bowed out following an unusual attempt to mix things up in one game with a cheeky underarm serve.
There were routine wins for two of Herbert's countrymen, as Richard Gasquet and Gilles Simon progressed in straight sets at the expense of Feliciano Lopez and wildcard Ernests Gulbis respectively.
