An interesting semi-final contest takes place on Saturday afternoon at the international Tennis Hall of Fame Championships, as towering Croat Ivo Karlovic clashes with young American Jack Sock for the fourth time on the professional tour. Karlovic leads the head-to-head series 2-1, yet Sock won their most recent meeting on clay in Houston last season. This will mark their first meeting on a grass cour

Up first in Newport, the tournament’s second seeded Ivo Karlovic defeated Dustin Brown in straight sets to advance to the semi-final stage of the tournament. He fired 23 aces en route to the 7-6(3), 6-3 win.

“When a guy hits 23 aces and doesn’t let you see any second serves, it’s going to be impossible to break him,” said Brown. “Then he had four aces, one return winner and one service winner in the tie-break. So there really wasn’t much I could do. Even in the second set. I double-faulted after he hit three return winners to get broken. In any other service game I could double-fault and nothing would have happened. You expect this going into the match, but it’s still very tough to lose a match like this.”

In a much shorter outing later on in the day, Jack Sock reached the semi-final round when his opponent Jan Hernych retired with a knee injury during the second game of the match.

This marks the fourth time that Karlovic and Sock will meet on the professional tour, with Karlovic leading the series 2-1. The Croat won the first encounter 3-6, 7-6(8), 6-2 last year in Indian Wells and followed up with a 7-6(4), 6-7(3), 6-3 victory last season in the Memphis quarter-final round. However, Sock found his way into the series when he beat the towering foe in straight sets on the clay courts in Houston. It will be interesting to see who holds the advantage on grass, as both men have played impressive tennis thus far.