Kevin Anderson overcame a first-set scare to move into the second round of the Erste Bank Open 500 in Vienna.
The South African, this year's Wimbledon runner-up to Novak Djokovic, overcame Georgia's Nikoloz Basilashvili in three sets.
But he had to recover from dropping the first set 6-4, before going on to claim the next two 7-6 (6) 6-3.
Sixth seed Borna Coric also fell behind in his first-round match, going a set down to Spain's Albert Ramos-Vinolas before recovering to win 6-7 (5) 6-0 6-4.
And there were also victories for Hungarian Marton Fucsovics - 1-6 6-0 7-5 - against Canadian Felix Auger-Aliassime and Andrey Rublev over Denis Kudla 7-6 (3) 6-0, but Milos Raonic came unstuck against Austrian Jurgen Melzer.
Melzer, currently ranked outside the world's top 400, claimed a straight-sets triumph, 7-6 (6) 7-5.
Cilic makes winning start in Basel
At the Swiss Indoors in Basel, there was an impressive start by third seed Marin Cilic, who saw off world number 29 Denis Shapovalov 6-4 6-2.
A straight-sets victory was also the order of the day for American wildcard Taylor Fritz, 6-0 7-5 against Serbia's Laslo Djere, but world number 175 Henri Laaksonen recorded a shock straight-sets victory over sixth seed Marco Cecchinato.
Swiss challenger Laaksonen delighted his home support by seeing off Cecchinato 6-4 6-2 in just 76 minutes, before Romania's Marius Copil completed the day's action by beating American Ryan Harrison 6-2 7-6 (8).
