Roger Federer struggled to hide his disappointment after his bid for a first US Open title since 2008 ended abruptly Tuesday with a five-set loss to Grigor Dimitrov in the quarter-finals.

The Swiss had defeated Dimitrov in all seven previous meetings but surrendered a two sets to one lead before sliding to a 3-6, 6-4, 3-6, 6-4, 6-2 defeat. Asked whether he felt he would have further chances to add to his record haul of 20 men's Grand Slam singles title, Federer replied: "I don't have the crystal ball."