The third-seeded Youzhny eased into the title match with a 6-3, 6-4 win over Germany's Michael Berrer, who was denied a return trip to the Zagreb final. He lost to Croatia's Ivan Dodig in last year's title match.
Lacko then advanced to his first career ATP final with a 7-5, 7-6 (7-3) win over sixth-seeded Marcos Baghdatis of Cyprus. Lacko was down 1-4 in the second set, but rallied to knock out the 2007 Zagreb champ.
Youzhny will appear in his 18th career final and will try for his eighth title. The Russian hasn't won since 2010 in Kuala Lumpur. He reached the quarterfinals at the Qatar Open to start 2012 and was a first-round loser to Andrey Golubev at the Australian Open.
Lacko, ranked 97th in the world, had a better result in Melbourne with a third-round setback to Rafael Nadal. The Slovakian is 0-3 lifetime against Youzhny, but the two haven't met since 2010.
The 2012 Zagreb champion will collect $90,000.