MISSION VIEJO, Calif. -- For a few hours of a sparkling mid-December morning in Southern California, two guys who figure to play a major role in the future of American men's tennis beat balls across the net of a neighborhood hard court.
On the other side of a chain link fence, a women's pickleball foursome click-clacked through a couple of sets, seemingly clueless about the identity of the two young men readying themselves for the start of the 2026 season. The yelps and chatter of a nursery school recess clattered down from a small hill overlooking the scene.
Across the globe, other members of the ATP Tour top 40 were likely going through their paces at exclusive clubs or those vaunted academies built on Rafael Nadal's or Patrick Mouratoglou's name. Alex Michelsen and Learner Tien were fine to do their thing in Mission Viejo, a way inland from Laguna Beach.
"I hate myself!" Michelsen screamed after a soft approach gave Tien an easy passing shot.
That brought out a little grin from the 20-year-old, who already has one of the great tennis poker faces. There would be a few more grins that morning, including one when Michelsen missed an easy volley.
"I should be shot!" he yelled.
Before long, they were playing a 10-point match tiebreak, with the rules according to the Next Gen ATP Finals, the tournament for the best players aged 20-and-under, that Tien went on to win a week later. Michelsen aced Tien with a serve that ticked the top of the net before dribbling over. He apologized.
"We can redo it if you're really sorry," Tien suggested.
"I'm not that sorry," Michelsen, 21, said. He won the tiebreak a few points later.
Within a few minutes, they were sitting on the bench beside the court, Michelsen asking Tien for some relationship advice from his partner in a climb to the top of their country's tennis mountain that started in the same Orange County hills. Sometimes, they were on neighboring courts at the same tennis center. More often, they shared fitness sessions on the beach.
Tennis moves fast. The current U.S. generation, led by Taylor Fritz, Frances Tiafoe and Tommy Paul, is suddenly a collection of players in their late-20s running up against time. All of them registered head-scratching losses during the season’s first week. Ambivalence has laced through Tiafoe’s relationship with tennis, though he has once again pronounced himself motivated and fit for purpose in Melbourne.
Paul was banged up for the final six months of the 2025 season. And Fritz, who has largely stood apart from his compatriots in how he has maximized his talent—regularly playing on the biggest stages against the biggest stars—is managing chronic tendonitis in his right knee.
Ben Shelton, 23 and the senior in Tien and Michelsen’s cohort, is the top-ranked American man now. Tien is seeded higher than Tiafoe. Michelsen already has plenty of big wins—a huge serve—tons of upside according to most high-quality tennis minds. At last year’s Australian Open, Shelton, Tien and Michelsen were three of four American men to make the second week. Paul was the other.
There’s a decent chance that practice match in Orange County in December may not have featured a chunk of the future of elite American men’s tennis but rather its present.
"It's always been a target in our minds that we want to catch those guys," Tien said as he sat beside the court. "I'm sure, on the other hand, that they they want to keep the lead on on us, and they want to keep their top spots."
Overtaking them—and then becoming competitive with Jannik Sinner and Carlos Alcaraz—will take some doing.
"At the top of the game, all the guys play very aggressively; they all have big strengths. Obviously, it's a goal to try and get there and compete with that."
Even Shelton, a two-time Grand Slam semifinalist who won his first ATP Masters 1000 title at an Alcaraz-and-Sinner-less Canadian Open last summer, didn't kid himself about being far off the pace that the world's two best players have set. And that was before he injured the left shoulder that is so vital to his power game.
"I could sit there and be like, 'Wow, 22 years old and I've been able to do these things and achieve these things,' but my mind is, I don't know, critical," Shelton said after losing to Sinner in the quarterfinals of Wimbledon.
"I'm a critical thinker. I'm trying to solve problems."
For now, Tien, Michelsen and Shelton all have the world's most precious commodity on their side: Time. Tennis is all about trying to take time away from the other player, to make them feel so rushed that they can't breathe, between shots and between points.
Time is also a friend to younger players. They haven't been around long enough to accumulate the scar tissue of losses and disappointment and unfulfilled dreams. Losses are learning experiences by default rather than by mental force.
They also possess another priceless commodity in sports and in life: Hope. Fritz, Tiafoe and Paul still have plenty of that but it's a different flavor. Their decade-plus in pro tennis serves as a constant check. At this stage of their careers, their improvements are likely going to be marginal yet could still bring massive reward.
"At some point it's not going to be me anymore," Fritz said of being the top American during a news conference Friday.
He isn't at the moment, but he says he doesn't care about that. Fritz would rather be the world No. 4 and the third-best American than the world No. 10 and the best of them. He roots for the crew of Americans, especially Tien and Michelsen. Fritz has been hitting with them and Ethan Quinn, another young Californian and the world No. 78, on practice courts since they were in their mid-teens.
"It's a natural progression," he said. "I'm getting old."
No one would say that Tien or Michelsen's are on their way to being old, but they have recently moved away from the coaches who guided them through their early pro careers, to work with seasoned tour veterans who know what it takes to get to the top. Tien hired Michael Chang, the 1989 French Open champion and a top-10 mainstay during the 1990s, in the middle of last season. Michelsen brought on Kristof Vliegen, a Belgian who helped Tallon Griekspoor rise from unranked nobody to the cusp of the top 20.
Vliegen, speaking as his charge sweated through a series of sprints, said that Michelsen’s physical gifts -- he’s 6-4, with long arms,a huge serve and soft hands -- made signing on with him late last year a no-brainer even if his footwork needs some foot work.
“In October when I was free,I had some calls and I said to everybody I’m not looking for a guy who’s 32 years old.I’m looking for a young guy,it doesn’t matter the ranking.A young guy that I can see that I can improve him or help him.I wanna be involved in the project that we have,and we will see how far we get with it.”
Time, health,luck,and mental fortitude will all play a role in determining that.Tennis-wise,Tien looks to be the more finished project.He has smooth,crisp shots and plays with a precocious level of control,built points and jumping on chances to tag the back of the ball for a lacing winner down or across the court.
This has taken him to a series of impressive wins over top-10 players,but they tend to beat him the second time around once they are familiar with the way he uses his left-handedness more effectively than just about anyone.Still,his mien helped him sneak up on opponents last year.He doesn’t look like the guy who is going to clean your clock on a tennis court.And then he does,shooting around the court like a cat,gettings his feet behind the ball and cracking it away.
“Obviously there are various aspects of his game that we are wanting to improve like his serve (which has improved a lot in such a short period of time) and fitness,” Chang wrote in an email. “He has no big weaknesses in his game so a lot of the focuses are on refining certain shots and making them better.”
At 5-11,Tien is undersized for a top pro these days and soft-spoken,halting at times in his speech,thinking before he speaks.He drives a small Tesla.Michelsen gets around in a BMW sport utility vehicle which he acknowledges is not exactly the hottest look for a young and rising sports star.His mother uses the car to drive the rest of the family around when Michelsen is away.
“I’m a big guy," he said."It works for me.”
Each seeks some of what the other one has.For Tien，an outstanding mover who rarely makes a bad decision during a point，a year of hardcore fitness work，even during the season，is starting to pay dividends.The puffy cheeks and baby fat of his rookie year are gone。
To the naked eye，his service motion appears to have new pop to it.Strength and flexibility work has helped him learn how to snap his spine with greater force to add velocity。
“It’s been a pretty big focus of mine for a while，”he said after collecting plenty of free points across two sets and the match tiebreak against Michelsen.“Baby steps.”
For Michelsen，who doesn’t rate his own serve all that highly，even though when he cracks it can sound like a thick tree-branch snapping，the chase is not for velocity but rather accuracy and placement，he said — and not just on his serve.
“The ball placement on every shot and just being a little more intentional,”he said.“I feel like I would just hit balls and not really think about where they’re going too much and you’ve got to be a little bit more focused on the court.I feel that comes with some maturity for me as well.”
He had a pretty good start last week in Brisbane,wining three matches — including one against Tien —and getting to the semifinals before losing to Daniil Medvedev,the eventual champion.
“I went three matches without losing my serve,”Michelsen said during an interview Friday.“I don’t think that’s ever happened in my life.”
Then there is the footwork, which rarely comes naturally to someone his size. After Michelsen and Tien finished their two hours of practice, Rodney Marshall, his fitness coach -- who occasionally also trains Tien -- showed up and dropped the cones on the court.
For the next 40 minutes, Michelsen danced and sprinted around the court, with Marshall timing all his moves. Tien watched from the side, thankful he was on orders to keep his legs fresh for the Next Gen Final. Still, he couldn't resist jumping in for a mano-a-mano final sprint. Michelsen nicked him.
Vliegen liked what he saw. He knows the best players in the world right now are the best movers. He wants to help make Michelsen as big and as fast as he can—the sooner the better.
"He's 21," Vliegen said of Michelsen."He's gunna have his best years probably from his 24,25,26 years old.These are going to be the years where he's going to be performing the best because he should be stronger mentally,stronger physically.You keep on building those things now;the chances are bigger that he's going to have a good peak at those moments;and if we get the peak earlier;I'm not here to wait for three or four years."
Tien’s and Michelsen’s similarities and differences make them a fascinating pair.They grew up close to each other in Orange County and spent their teen years competing and practicing with each other.
Both estimate that they have hit more balls with the other guy than they have with any other person.Michelsen is the rare pro who is unbothered by Tien’s left-handedness even though most of his opponents are right-handed.A tennis ball is a tennis ball.He sees it.He hits it.It’s not that deep.Both are intensely competitive though they disguise in different ways.Like Vliegen，他们不想等待，但他们也意识到自己没有太多选择。
Michelsen may never move like Alcaraz.Tien probably won't ever have the power of Jannik Sinner.For now，though，他们有时间，时间来工作，希望这一切有一天能为他们聚集在一起。
与此同时，聚光灯来了，因为比赛在移动。他们想要他们的时间现在就到来。越来越多的迹象表明，这将会发生。