Karlovic kills Ymer momentum

World number 549 Mikael Ymer had stunned Fernando Verdasco – ranked 505 places above him – in the first round for his maiden ATP Tour win but veteran Ivo Karlovic proved an obstacle too far.

Ivo Karlovic in action.

Ivo Karlovic put the brakes on Mikael Ymer's Stockholm Open fairytale with a come-from-behind victory in Wednesday's second-round match.

World number 549 Ymer had stunned Fernando Verdasco – ranked 505 places above him – in the first round for his maiden ATP Tour win. But powerful veteran Karlovic proved an obstacle too far, the 37-year-old earning a 4-6 6-4 6-4 triumph. 

Juan Martin Del Potro beat John Isner 6-4 7-6 (8-6) in a first-round contest, while Germany's Alexander Zverev beat Adrian Mannarino 7-5 6-4 to reach the quarter-finals.

Jack Sock and Jurgen Zopp were first-round victors in Wednesday's other matches.