Spain's Pablo Carreno Busta overcame battling qualifier Denis Shapovalov to reach the US Open quarter-finals for the first time.
The world number 19 beat the 18-year-old Canadian 7-6 (7-2) 7-6 (7-4) 7-6 (7-3) in an entertaining encounter.
Shapovalov, ranked 50 places below his opponent, hit eight aces and 54 winners as he pushed Carreno Busta all the way.
However, the 12th seed remained composed to dominate the three tie-breaks and reach the next round.
Carreno Busta will face either France's Lucas Pouille or Argentine Diego Schwartzman next.
This is the second time he has reached the quarter-finals of a Grand Slam after making the last eight of the French Open in June.