Five-time champion Roger Federer is out of the US Open after Bulgaria's Grigor Dimitrov won a late-night thriller to finally beat the Swiss great.
Federer, 38, had won all seven of their previous meetings but Dimitrov fought back for a memorable 3-6 6-4 3-6 6-4 6-2 win in New York.
Federer was hampered by injury in the latter stages, allowing unseeded Dimitrov to run away with victory.
Dimitrov, 28, will play Russian fifth seed Daniil Medvedev in the last four.