In the all-Serbian tournament, Erste Bank Open in Vienna Novak Djokovic beat Filip Krajinovic. in the first-round tie.
Djokovic overcame a slow start, saved a set point, before beating Filip Krajinovic 7-6 (7-6) 6-3 to set up a meeting with Borna Coric in the second round.
World No 1 Djokovic broke for a 3-1 lead but went down in the next four games against his regular hitting partner. Krajinovic then missed a set point at 6-5 in the tie-breaker.
Djokovic grabbed the advantage to surge ahead in the match before going on to wrap up the win, thanks to a more solid second set showing.
On the other hand, Dan Evans progressed to the second round after former Great Britain team-mate Aljaz Bedene retired.
Evans was in a strong position, leading 6-3 4-5 when the Slovenian could not bear to go along in the match and called time on the match after suffering a right thigh injury.
Bedene, who changed allegiance from Slovenia to Britain and then back again, suffered the problem early in the match, but could not continue.
There was not much of a contest between the two men, with Evans, who made the semi-finals in Antwerp last week, claiming the first set with a solitary break before fending off several break-back points in the next game.
The second set was on serve but Bedene retired at a curious time, having just won a game which would have left Evans serving to stay in the set.
The British No 1 Evans couldn’t have asked for more who will now play Jurij Rodionov in the second round after the young Austrian stunned Denis Shapovalov.