British number three Dan Evans is through to the last-16 of the Delray Beach Open in Florida after he beat defending champion Frances Tiafoe.
Tiafoe served for the match at 6-5 in the second set, but Evans broke the Frenchman and won the tie-break 7-1.
World number 148 Evans, 28, then lost serve at 5-4 up in the third, but eventually prevailed 3-6 7-6 (7-1) 7-5.
Argentina’s Juan Martin del Potro won his first match of the year as he returned from a fractured kneecap.
The world number four, who missed last month’s Australian Open, beat Japan’s Yoshihito Nishioka 6-3 7-5.
He will play American Reilly Opelka in the last 16, while qualifier Evans faces South African wildcard Lloyd Harris.
American second seed John Isner beat Canadian Peter Polansky 6-3 7-6 (7-4) and faces unseeded Slovakian Lukas Lacko in the next round.