Canadian top seed Milos Raonic was ousted from the ATP Atlanta Open on Wednesday as US teen Brandon Nakashima rallied to advance into the quarter-finals.
Nakashima, ranked 115th in the world, outlasted world number 22 Raonic 5-7, 6-3, 7-6 (7/4) after two hours and 12 minutes.
Raonic, the 2016 Wimbledon runner-up, was a wild card entrant who had not played since Miami in March due to a nagging calf injury.
Nakashima, who turns 20 on Tuesday, is coming off a run to his first ATP final last week at the Los Cabos event in Mexico, where he lost to Britain's Cameron Norrie.
Nakashima will play for a spot in the semi-finals on Friday against Australian Jordan Thompson, who defeated German qualifier Peter Gojowczyk 7-6 (8/6), 6-4.
Also advancing on Wednesday was US fifth seed Taylor Fritz, who downed compatriot Steve Johnson 6-7 (5/7), 6-4, 6-1.
Italian second seed Jannik Sinner, ranked 23rd, plays for a spot in the quarter-finals on Thursday against Aussie qualifier Christopher O'Connell. Sinner lost his first ATP final in Miami to Poland's Hubert Hurkacz.
Results from the ATP Atlanta Open on Wednesday (x denotes seed):
Brandon Nakashima (USA) bt Milos Raonic (CAN x1) 5-7, 6-3, 7-6 (7/4)
Taylor Fritz (USA x5) bt Steve Johnson (USA) 6-7 (5/7), 6-4, 6-1
Jordan Thompson (AUS) bt Peter Gojowczyk (GER) 7-6 (8/6), 6-4