Luxembourg's Gilles Muller downed towering Croat Ivo Karlovic in the Netherlands on Sunday to claim the title in 's-Hertogenbosch in a final with the oldest combined age for two players since 1976.

Muller, 34, beat 38-year-old Karlovic 7-6 (7/5), 7-6 (7/4) in a showdown of two of the game's biggest servers to lift his second tour-level trophy, following January's triumph in Sydney.

It was the oldest men's singles final since Ken Rosewall (42) and Ilie Nastase (30) went head-to-head in Hong Kong 41 years ago.

Muller smacked 22 aces to Karlovic's 19 with not a single break point for either player as the Luxembourger atoned for last year's final defeat in the Netherlands to Nicolas Mahut.

He next heads to Queen's where he faces Georgia's Nikoloz Basilashvili in the opening round of the Wimbledon warm-up event.