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American Tommy Paul continued his title defence at the Dallas Open while several of his countrymen fell during an upset-filled day.

Paul, seeded third, defeated close friend Ethan Quinn 6-4, 5-7, 6-4 to reach the quarter-finals of the ATP 500. The 27 year-old served for the match at 5-4 in the second set and let slip four consecutive points after taking a 30/0 lead. The 2023 NCAA singles champion Quinn built upon his momentum, grabbing the next two games to force a decider.

Paul avoided repeat drama serving for the match at 5-4 in the final set, instead closing the two-hour, 13-minute match.

“I’ve been in these situations a little bit more,” Paul said when addressing the difference maker in the match. “I felt a little more comfortable probably. That’s how you win the big matches, being better in the big moments. I tried to do that today. It would’ve been nice to serve out the second set, but do it in three.”

Up next for Paul is 6’11” Reilly Opelka, who rallied past Cameron Norrie 4-6, 7-6(5), 6-4 after hammering 18 aces during a two-hour, 30-minute battle. Despite hailing from the same country and sharing the same birthyear, Paul and Opelka will meet for the first time.

In a day of American upsets, Canadian Denis Shapovalov ousted top seed Taylor Fritz 2-6, 6-3, 7-6(2) to score his first Top 10 win since defeating Fritz en route to the 2022 Vienna final. Fritz came out firing, not committing an unforced error through the first seven games. But the 25-year-old lefty found rhythm behind his hefty delivery in crucial moments, crushing 15 aces and saving seven of the nine break points he faced.

“It feels incredible obviously. Taylor is a super tough opponent… He came out super solid and I came out a little sluggish,” Shapovalov said. “It was difficult. I’m definitely happy with my fight. I’m happy I was able to turn it around in the second set and I was able to keep that momentum going."

Shapovalov next meets sixth-seeded Czech Tomas Machac, who defeated Australian Rinky ^Hijikata 6-4, 7-6(0).

Fifth seed Frances Tiafoe fell to Yoshihito Nishioka. The Japanese lefty earned a hard-fought 3-6, 6-4, 6-3 win to snap a 16-match losing streak against Top 20 players. 

Spaniard Jaume Munar upset fourth seed Ben Shelton 6-2, 7-6(3) to earn his second Top 20 win of the season.

Munar converted both break point opportunities according to Infosys ATP Stats while he raced into a 4/1 lead in the second-set tie-break to seal the biggest win of his season after one hour and 35 minutes.

“I’ve been performing well the last couple of weeks,” Munar said. “I feel like everything is paying off now, but I’ve been working since two, three years ago on many things. I’ve been changing my game, trying to be more aggressive and I feel like I’m starting to be confident in it.”

Munar  will next meet Matteo Arnaldi.

Second seed Casper Ruud ousted American qualifier Michael Mmoh, who was competing in his first tour-level event since last April. The Norwegian scored a convincing 6-1, 6-4 victory in 70 minutes. Ruud, who next plays Nishioka, is aiming for his second hard-court trophy and first since 2021 in San Diego.

“The plan was to step up and play a little more aggressive than the first round and I think I did that really well,” Ruud said. “Not too many unforced errors. Not too many errors in general. I was controlling many rallies, trying to stress him in a way, play heavy — of course patient when I had to.

“Any time I got a small chance, I wanted to come in and rush him and I think I did well. I’ve been practising this a lot back home, coming into the net. Very happy with that performance, challenging myself to play a bit outside of my comfort zone.”

Arnaldi beat Alejandro Davidovich Fokina 6-1, 6-3 after winning 81 per cent (25/31) of his first-serve points. The eight-seeded Italian is into his first tour-level quarter-final since last August, when he reached the semi-finals at the ATP Masters 1000 event in Montreal.