The Spaniard's fifth title of the season moves him back ahead of 23-time Grand Slam champion Novak Djokovic at the top of the rankings.
The 20-year-old Spaniard came through 6-3, 6-4 and will face Australia's Alex de Minaur, who beat second seed Holger Rune 6-3, 7-6 (7/2), in Sunday's final
Andy Murray makes a winning start to his grass-court season with a straight-sets win over qualifier Yen-Hsun Lu at Queen's Club.
