The 20-Year Age Gap: John Isner to battle red-hot teen Alex Michelsen in Newport semifinals 

WATCH: Isner Features In TC Original "Daily Pro"

Could a fifth Infosys Hall of Fame Open trophy be written in the stars for John Isner? The 38-year-old is two wins away from making that happen in Newport, R.I., though will need to cool off a red-hot opponent 20 years his junior in Alex Michelsen.

Both competitors prevailed in all-American matchups on Friday. Isner eliminated the tournament’s top seed, Tommy Paul, completing a 4-6, 6-3, 7-6 (4) comeback after being two points from exiting on four occasions. Down to No. 126 in the ATP rankings this week, Isner fired 20 aces in moving to 3-0 against Paul. The two were facing off for the first time since the 2020 Acapulco quarterfinals.

“He was way better than I was in the first set. The first two holds in the second set were actually very critical,” Isner told Blair Henley afterwards. “That kind of gave me free rein to go after my returns. I told some fans back there I hit the best return I’ve ever hit in my life.

“It was no secret I did not want to rally with that guy towards the end of the match, so I was gonna serve and volley and roll the dice that way.”

Isner arrived to the ATP 250 grass-court event just 4-9 on the season and was on a seven-match losing streak that began in the Dallas Open final when he missed four championship points against Wu Yibing. He’s looking to return to the winners’ circle for the first time since capturing his 16th career crown in Atlanta two years ago. A win Saturday would enable the Greensboro, N.C. native to get back inside the Top 100.

His next hurdle should prove an intriguing test. Michelsen picked up the ATP Challenger title in Chicago last weekend, then carried that momentum over to the site of the International Tennis Hall of Fame.

The 18-year-old has now celebrated his first three ATP Tour match wins, today adding a 6-3, 6-3 victory over fourth seed Mackenzie McDonald. Michelsen converted four breaks of serve to sweep past his countryman after 72 minutes.

"I served really well, first-serve percentage was probably pretty high. I was looking at the stats after the match," Michelsen said. “Hit a bunch of aces. The serve was key today and I didn't miss too many groundstrokes either, so that was nice.”

In the opening round, Michelsen ousted defending champion Maxime Cressy and followed it up with a second straight three-set rally against James Duckworth. The top recruit in the Class of 2023 has committed to play for Isner’s alma mater—the University of Georgia—starting this fall, though there's always a chance his rapid rise impacts those plans. Michelsen was ranked No. 600 at the start of 2023; he’s now on the cusp of a Top 150 debut and will go well beyond that marker with a win over Isner.

“He’s just very confident. I was in that position before. You kind of come out of nowhere. Not many people know how you play, don’t expect much out of you,” Isner said when assessing the matchup.

“He obviously knows his way around a grass court. I’ve seen him play and I think he’s got a lot of skill. There’s a lot of nuance to his game, which is very impressive at 18 years old. I expect a tough match. It’s gonna be tight, that’s for sure. He’s a heck of a player.”

France’s Adrian Mannarino and Ugo Humbert, who both advanced Thursday, will battle it out in Saturday's first semifinal.