Ivo Karlovic defeated world No. 79 Simone Bolelli of Italy in their first-round match at the Kremlin Cup on Wednesday.
The big-serving Croatian, ranked 130 in the world, had to dig deep to secure a 6-4, 7-6(4) win.
In round two, the 33-year-old veteran will face local favorite Alex Bogomolov Jr., who upset three-time champion Nikolay Davydenko in the first round, in his quest for a fifth career title.
Elsewhere, tournament newcomer Poland’s Jerzy Janowicz beat world No. 80 Benjamin Becker of Germany in straight sets.
Janowicz, ranked 74 in the world, overcame tough resistance for a 7-6(6), 6-3 victory.
The Polish 22-year-old will play seventh seed Carlos Berlocq of Argentina in the second round.
Earlier, Japanese eighth seed Ito Tatsuma dispatched qualifier Konstantin Kravchuk of Russia 7-6(7), 2-6, 6-3.