Top seed Juan Martin del Potro defeated qualifier Grega Zemlja in Sunday's final at the Erste Bank Open.

Del Potro beat Zemlja by a 7-5, 6-3 margin to capture his third title of 2012. The Argentine lost to Jo-Wilfried Tsonga in last year's Vienna final.

The former U.S. Open champ also won in Marseille and Estoril this year, while losing in the Rotterdam final to Roger Federer. Del Potro was also the bronze medalist at the London Olympics.

Del Potro now has 12 career singles titles.

"I'm so happy. It's important to have a good end of the year," del Potro said. "I'm looking forward to keep improving, keep playing well at the same level as I had here."

Zemlja beat three seeds -- No. 8 Xavier Malisse, No. 3 Tommy Haas and No. 2 Janko Tipsarevic -- to reach his first ATP Tour final.

Del Potro and Zemlja met for the first time on Sunday.

With the win, del Potro collected $113,795.