In the hunt for his first tour-level title since 2021, Tommy Paul moved one step closer to his second ATP Tour trophy Friday at the Dallas Open, where he overcame German Dominik Koepfer 7-5, 6-3 in the quarter-finals.

Five breaks of serve were featured in the first set, with the second seed Paul earning a crucial break at love in the 11th game to gain a one-set advantage. The World No. 15 pounced on any look at Koepfer's second serve and produced all-court coverage to reach his first semi-final since last year's ATP Masters 1000 event in Toronto.

Despite letting slip a 40-0 lead in the final game, Paul closed the one-hour, 28-minute contest on his fifth match point.

"Not the prettiest match, he definitely makes it super tricky for me," Paul said of the lefty Koepfer. "He's behind the baseline cranking balls, changing direction all the time. It's a super tricky matchup, but I'm obviously happy to get through that match."

The 26-year-old Paul will meet Ben Shelton in an all-American semi-final after the third seed's 6-7(2), 6-4, 6-4 victory against Jordan Thompson.

Shelton lost the opening set despite not facing a break point, but showed great mental strength to recover and close out sets two and three with marathon holds. The 21-year-old fought off three break points to clinch the second set and then erased four in the final game of the match before sealing victory with a forehand winner on his second match point.

"I think any time you can come back and get a win after losing the first set it's impressive, especially against someone who serves as well as Jordan does indoors," Shelton said post-match. "He presented so many problems today. I had to problem-solve the whole match. I'm really glad that I was able to get through it and I thought I played really well."

HEAR HIM ROAR 🤩@BenShelton completes the comeback against Thompson 6-7(2) 6-4 6-4 and books his semi-final spot! 🔥@DALOpenTennis | #DALOpen pic.twitter.com/HGvf73RrpP

— ATP Tour (@atptour) February 10, 2024

Shelton holds a 2-1 lead in his Lexus ATP Head2Head series with Paul, with all three meetings coming in 2023. After Paul won in the Australian Open quarter-finals, Shelton gained revenge in the US Open fourth round before again beating Paul en route to his first tour-level title in Tokyo.

Marcos Giron opened Friday's evening session in Dallas with a 6-1, 6-4 upset of top seed Frances Tiafoe. It was the Giron's first Top 20 win since he beat Felix Auger-Aliassime to reach the Tokyo semi-finals last October, and he secured the victory without facing a break point in a commanding performance.

Giron won his first Lexus ATP Head2Head meeting with Tiafoe at the Rolex Paris Masters in 2021, but had lost his previous seven sets against his countryman across three defeats. His semi-final opponent will be fourth seed Adrian Mannarino, who led James Duckworth 6-2, 3-1 before the Aussie retired.