Who Is Learner Tien’s Coach, Eric Diaz? Everything You Need to Know About the Brains Behind the ATP Pro’s Success

Learner Tien is quickly becoming a name tennis fans recognize. At just 19 years of age, Tien broke into the Top 200 and snagged three ATP Challenger Tour titles at Bloomfield Hills, Las Vegas, and Fairfield respectively. If that was not enough, she cleared the AO qualifiers and has now raced into R2 of the Melbourne Major. It’s an impressive achievement for such young talent. But who’s behind his success?

It isn’t just one person shaping Tien into the player he is today. His journey has deep roots thanks to his family and coaches. Growing up in a household where both parents played recreationally, Tien was introduced to tennis early on. He hit balls with his family at community courts in Irvine, California. As he showed more interest in the sport, his dad, Khuong, became his main coach until Learner joined the USTA player development program around the age of 10-11. It was during his teen years that he met Eric Diaz, who became his first official coach and has been by his side ever since.

Diaz comes from a tennis family himself—his father is the legendary University of Georgia men’s coach Manny Diaz—which gives him a unique perspective on coaching young talent. When he first saw Tien, he noted that the young player had an “aura” around him. “Everybody anticipated some big things for him,” Diaz recalled recently, “but he was just a quiet kid.” That quiet confidence has led to some major wins on the court; Tien clinched the USTA Boys’ 18s National Hard Court Championships twice at ages 16 and 17. His big moment came when he reached his first ATP Tour quarterfinal at the Winston-Salem Open, making him the youngest American man in the Top 200 since Stefan Kozlov back in 2016.

Additionally, Tien’s junior career was nothing short of impressive. He peaked at No. 4 in the rankings and made it to the finals of both the Australian Open and US Open in 2023. Notably, he also took home the boys’ doubles title at the Australian Open with partner Cooper Williams. This only set up the stage for him going into the next season.

However, Tien’s journey hasn’t been without its bumps. In June 2024, he faced a setback with a seventh-rib fracture that kept him off the court for over three months. Diaz took a cautious approach to Tien’s return: “We kind of held off his return to tournaments about six to seven extra weeks, so we really just wanted to clean some stuff up and we did a lot of work on the forehand and on the serve.” This strategy paid off when he came back strong, winning his first 28 matches and qualifying for the Next Gen ATP Finals.

Now heading into the Australian Open, Tien’s team is feeling confident about his improvements and potential success against tough opponents like Daniil Medvedev. Does his team believe he’s ready for this challenge? Absolutely!

Learner’s team on his improvements so far

Despite his impressive run last season, Learner Tien, along with coach Eric Diaz and the rest of his team, remains focused on improvement. They understand that at just 19 years of age, Tien has a long road ahead in his tennis career. Speaking on the ATP Tour website on January 15, Tien noted, “I think sometimes when you’re winning and having success, it can be hard to tweak things.” Noting his improvement over the past year, he added, “It’s honestly nice for me to know that there’s a lot of stuff that I can still improve.”

Diaz echoed this sentiment, explaining that they have changed “a handful of things” in Tien’s game, particularly focusing on his serve and forehand. “His second round of qualies, he hit 16 aces, two double faults,” the coach added, noting the trouble Tien went through when facing Jozef Kovalík to win 6-3, 6-4 on January 9. Diaz further pointed out. “But for him to be able to win while not having a very good serve day says a lot about his mentality.”

Tien showcased his skills in the first round of the Australian Open, defeating Camilo Ugo Carabelli in a hard-fought five-set setter by 4-6, 7-6 (3), 6-3, 5-7, 6-4 to advance to the second round. It’s not going to be an easy one though. His next opponent is the three-time Australian Open finalist Daniil Medvedev. Do you think Tien will surpass expectations and deliver a surprise upset? Let us know your thoughts in the comments below.