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"[He] obviously is a guy who's a great server. Actually, I beat him in my match to make the Top 100 and he bagelled me in the first set that match. so not an easy matchup for me," Shelton said. "To break him three times tonight is something I take a lot of confidence from and moving forward into the rest of the tournament, feeling really confident."

The fourth seed only delivered six aces, but won an overwhelming 90 per cent of his first-serve points. With that serving performance, the lefty was able to finish the match without facing a break point.

Shelton is pursuing his first ATP Tour title of the season this week. The 22 year-old is at a career-high No. 13 in the ATP Rankings and keen to continue his climb.

"I don't think it's an overnight thing. Maybe it's a little bit of an evolution, but I think just the steady work paying off," Shelton said. "I didn't see as many big results last year as I wanted to, but the work was there every single day."

Next up will be China's Buyunchaokete or Spaniard Jaume Munar. 

Casper Ruud battled past another, Australian, lucky loser James Duckworth, defeating last year’s quarter-finalist 7-5, 4-6, 6-3. In the deciding set, the Norwegian dug out of a 0/40 hole in two service games. Ruud’s serving performance under pressure was crucial en route to his two-hour, 10-minute victory, during which he saved 10 of the 11 break points he faced.

“James is a really tricky player. He plays fast. He likes the lows shots coming in,” Ruud said. “Typical kind of play style I’ve struggled with on this surface before. Happy to pull through. It wasn’t always the cleanest.

“I saved a lot of break points when I had to, which was key, and I played well behind my serve on the really important points.”

Seeded second, Ruud will next face Roberto Carballes Baena or American qualifier Michael Mmoh. The 26 year-old Ruud is competing in his first tour-level event as a Top 5 player since the 2023 US Open.