Karlovic topples Monaco

Ivo Karlovic knocked out defending champion Juan Monaco to reach the semi-finals of the Dusseldorf Open.

The 6ft 10in Croatian was playing his first clay-court quarter-final in more than three years and served 19 aces in a 6-4 3-6 6-3 victory.

Next up Karlovic will face 20-year-old Czech Jiri Vesely, who reached his first ATP Tour semi-final with a 6-1 6-1 win over veteran Jurgen Melzer.

It was a miserable 33rd birthday for Melzer but a big moment for his young conqueror.

"It's amazing," said Vesely on "It was one of my goals this year to reach the final rounds of an ATP event, and I'm very happy that I made it right before the French Open."

Top seed Philipp Kohlschreiber will have to finish his quarter-final on Friday after bad light intervened with the German leading Mate Delic 7-5 4-4.

The winner will meet Denis Istomin, who knocked out third seed Andreas Seppi 6-3 6-4.