The 6-foot-10 Croat closed out the win on his second match point with a 140-mph ace. He arched his back and clenched his fists before going over to shake hands with his coach.

Karlovic broke Zabaleta in the second game of the final set and again three games later to go up 5-1. His fastest serve of the day was clocked at 149 mph. He had 10 aces in the match and finished the week with 53.

"I am really excited because it's my first title and it's on the clay, which is unbelievable," Karlovic told the crowd just after the match. "I'm really happy with the way I was playing all week."

Zabaleta failed to capitalize on five break-point chances in the first set and one in the second.

"I had many chances in the beginning of the match and maybe if I had broken I think maybe it was different," Zabaleta said later. "He's too strong."

Karlovic beat two seeded players to reach the final. Karlovic beat sixth-seeded Benjamin Becker and No. 2 seed Tommy Haas, both of Germany.

The Croat earned $65,850 for his first tour title since beginning his professional career in 2000.

It was Karlovic's third final. He was runner-up to Andy Murray of Scotland in San Jose, Calif., earlier this year and in 2005 to American Andy Roddick at Queen's Club in London.

"It is an unbelievable feeling," Karlovic said later. "In the beginning I was a little bit nervous. I was telling myself, 'If it's meant to be, I'm going to win. If not, it was my third final.' I really wanted to win."

Zabaleta had a tough time returning the Croat's serve. Zabaleta won only nine points on Karlovic's 41 successful first serves.