Tommy Paul saved a match point to defeat top seed Alexander Zverev 4-6 7-6(6) 6-4 and reach the quarter-finals of the Cincinnati Open on Wednesday after a nearly 90-minute rain delay.
German world number three Zverev took the first set and trailed 3-4 in the second before the fourth-round match was suspended due to rain.
Paul emerged from the lengthy delay looking the sharper player, saving a match point before levelling the contest as Zverev struggled to find his rhythm.
The German took a 4-2 lead in the third set but Paul dug his heels in to take control of the match, rallying to win four straight games in a stunning comeback to advance to the quarter-finals in Cincinnati for the first time.
Zverev's 14 aces were accompanied by nine double faults, with his service game looking shaky at times after he was called for a foot fault in the third set.
Paul will next play Flavio Cobolli after the Italian earlier defeated Spain's Rafael Jodar 4-6 7-6(3) 6-3.
(This story has been corrected to fix the spelling of 'quarter-finals' in the headline)
