Ben Shelton upsets World No. 4 Jannik Sinner at Shanghai

Ben Shelton upset World No. 4 Jannik Sinner 2-6, 6-3, 7-6 (5) in fourth-round action Tuesday at the Shanghai Masters in China.

The upset win — which earned Shelton his first trip to an ATP Masters 1000 quarterfinal — was a belated birthday present. Shelton turned 21 on Monday.

"To think that a year-and-a-half ago I was in college, and a year ago playing Challengers, now I am on center court in Shanghai with the crowd singing, 'Happy birthday,'" Shelton said after the match. "It is one of those pinch-me moments."

Shelton notched 15 aces as he powered through the 2-hour, 32-minute match, building momentum as he went and not letting slips drag him down. Despite losing a 4-0 lead then falling behind 4-5 in the third-set tiebreak, Shelton came back to win the final three points for the win over the Italian.

"I had a lot of belief in my ability to serve and hang tough and to make it deep in sets," Shelton said. "I trusted my fitness levels, being able to go the distance. That gave me a lot of confidence. My serve wasn't working that well in the first set, I felt that he was really on top of me. I really started to find my groove and had one of my best serving days in the second and third sets."

Shelton will next face fellow American Sebastian Korda, who posted a 7-5, 7-6 (6) win over Argentine Francisco Cerundolo to reach his second Masters quarterfinal.

Hungarian Fabian Marozsan took three sets to knock off eighth-seeded Norwegian Casper Ruud 7-6(3) 3-6 6-4. Despite recording 14 aces and rallying to win the second set, the current World No. 9 couldn't hold off Marozsan.

"It's not easy to finish the match. This is the highest level, where we're playing at right now. Casper is a great player," Marozsan said after the match. "This is one of my best results in the last few years. I'm just getting into the top 100, so I'm really happy to just be playing at this level."

Maroszan is set to face 16th-seed Hubert Hurkacz, who outlasted hometown favorite Zhang Zhizhen 7-6 (6), 4-6, 7-6 (4).

"Zhang was playing some really amazing tennis. It was a battle," Hurkacz, of Poland, said. "We were both giving it all out there, leaving everything. Hopefully the fans enjoyed that match because I think that was a really high level. If you just left a little bit of space out there, you're running and fighting from behind."

—Field Level Media