Karlovic edges past Dimitrov
Ivo Karlovic booked his spot in the second round of the PBZ Zagreb Indoors after recording a 7-6 (7-3) 7-6 (7-3) victory over seventh seed Grigor Dimitrov.
The big-serving Croatian sent down 18 aces to his opponent's 10 in a contest which did not feature a single break point.
Karlovic, a native of Zagreb who is aiming to get beyond the quarter-finals for the first time, completed the victory in an hour and 30 minutes.
Elsewhere, fifth seed Martin Klizan fought back to claim a 4-6 7-6 (8-6) 6-1 victory over Italian lucky loser Matteo Viola, who was a set and a break up at one point.
Blaz Kavcic, Nikola Mektic, Somdev Devvarman and Grega Zemlja also won their first round matches on Tuesday, the latter setting up a second-round clash with top seed and two-time champion Marin Cilic.