'S-HERTOGENBOSCH (NETHERLANDS) - Luxembourg's Gilles Muller won the battle of aces against big-hitting Croat Ivo Karlovic to reach the 's-Hertogenbosch final in a closely fought contest on Saturday.
Luxemburg's Gilles Muller returns the ball during the men's first round match at the Roland Garros 2016 French Tennis Open in Paris on May 24, 2016
Muller, ranked 44th in the world, slammed down 22 aces to 21 by the towering Karlovic, who holds the world record for career aces, for a narrow 7-6 (7/5), 7-6 (7/4) win at the grasscourt tournament in the Netherlands.
Muller will bid for his first career trophy on Sunday against either French title-holder Nicolas Mahut, ranked 49, or American Sam Querrey (37).
CoCo Vandeweghe eased into the women's final, beating fellow American Madison Brengle 6-4, 6-2.
Vandeweghe, ranked 43rd, will bid Sunday for a second title in the event, after 2014, when she plays France's Kristina Mladenovic.
The 32-ranked Mladenovic defeated Swiss top seed and close friend Belinda Bencic 2-6, 6-3, 6-4.