Karen Khachanov won his sixth ATP tour title at the Qatar Open after he defeated teenager Jakub Mensik in straight sets 7-6 (14-12) 6-4.
World number 17, Khachanov, 27, of Russia, did not drop a set in the tournament.
Czech player Mensik, 18, was the first teenager to reach the Qatar Open final.
Mensik hit 16 aces in the final and Khachanov said: "For a minute, I thought I was playing John Isner and not Jakub Mensik today."
Mensik, who is ranked 116th in the world, had beaten Andy Murray and world number five Andrey Rublev en route to the final.