DELRAY BEACH, Fla. -- American qualifier Christian Harrison upset top-seeded Cristian Garin of Chile 7-6 (3), 6-2 Saturday in the second round at the Delray Beach Open.
Harrison, ranked No. 789, squandered three consecutive set points serving at 6-5 in the first set and lost serve, but regrouped to dominate the tiebreaker. He swept the final four games of the match to become the second-lowest-ranked quarterfinalist in tournament history.
Juan Martin del Potro was ranked No. 1,042 when he reached the quarters in 2016.
No. 2-seeded John Isner of the United States hit 22 aces, never faced a break point and beat Thiago Monteiro of Brazil 6-4, 7-6 (4). Isner next plays Sebastian Korda, who rallied to win an all-American match against No. 5 Tommy Paul 4-6, 6-3, 6-2.
Harrison, the 26-year-old brother of tour veteran Ryan Harrison, has been plagued by injuries during his career.
"I just love the sport, I love what I'm doing,'' he said. "I just can't wait to keep playing and hopefully have a good, healthy next couple of years.''
Garin, who had a first-round bye, came into his first match of 2021 ranked a career-best No. 18. He said Harrison made the most of the cool afternoon weather.
"These conditions are good for him," Garin said. "He played really flat, really fast. I hope he can play like this the rest of the year.''
Harrison next plays Gianluca Mager of Italy, who advanced by beating No. 6-seeded Sam Querrey of the United States 7-6 (8), 6-1.