Fernando Verdasco will take on fellow Spaniard Marcel Granollers, while home favorite Marin Cilic will face defending champion Aleksandr Dolgopolov in the semifinals of the Croatia Open on Saturday.
For the first time since the tournament was first held in 1990, the top four seeded players will compete for a place in the final.
Top-seeded Verdasco defeated Russian wild card Andrey Kuznetsov 6-2, 6-2 on Friday, while Granollers rallied to beat Germany's Matthias Bachinger 1-6, 6-3, 7-5.
Verdasco, the 2008 champion, saved all six break points he faced and converted three of seven break chances.
''Obviously, I am very happy with the way I progress here,'' Verdasco said. ''Being in the semifinals is a very good thing. I played really good today.''
Fourth-seeded Granollers lost the first set in just 31 minutes. He had a 5-3 lead in the third set, but then lost serve before breaking again for his victory.
Second-seeded Cilic beat American Wayne Odesnik 6-4, 6-0 and third-seeded Dolgopolov defeated Carlos Berlocq of Argentina 6-4, 6-4.
''I needed a few games in the beginning to adjust,'' Cilic said. ''I played very well when I needed it.''
