ST. LOUIS – Homegrown athletes Jayson Tatum and Matthew Tkachuk are conference finals-bound and thriving in their young basketball and hockey careers.

Many years before their big achievements, believe it or not, both crossed paths in middle school. A recent report from St. Louis Post-Dispatch reporter Ben Hochman reflects on their years-long friendship. Bleacher Report also learned they spent time together in a middle school gym class before their journeys as professional athletes.

And there’s one unique discovery that went viral last week and bring this all together. A 10-year-old video resurfaced in popularity on YouTube that shows Jayson Tatum and Matthew Tkachuk, as teenagers in the same high school gym.

It appears the video was part of a school project for Tatum, who used it to explain why he chose to spend his high school years at Chaminade College Preparatory School. He gives credit to the basketball program, then quickly adds “another reason why I came to Chaminade is because of great people and great fans.” Four friends join Tatum in the video. One of them, none other than Matthew Tkachuk.

“Great guys,” Tatum said of Tkachuk and his three other friends. In the video, Tatum is speaking into a microphone and Tkachuk is dancing with a tablet in his hands. The video then proceeds with Tatum’s friend Graham sitting down with him for a one-on-one conversation about Chaminade.

Tatum and Tkachuk, now stars for the Boston Celtics and Florida Panthers, both attended Chaminade College Preparatory School from sixth to ninth grades. The private school teaches kids between the sixth and 12th grade levels.

After ninth grade, Tkachuk went on to join the United States Hockey League. Tatum stuck at Chaminade and graduated from high school in 2016.

Tatum’s primary high school coach, Frank Bennett, told FOX 2 last year on Tatum, “he’s a guy that has everything at his fingertips and is still a grounded down-to-earth guy.”

Tkachuk agrees. In a recent interview with Bleacher Report, said he remembers Tatum as a confident and friendly guy. In gym class, Tkachuk had the chance to see Tatum’s talents up close.

“I don’t know if he called his shot, but he’s like, ‘Yeah, I’m going to the NBA.’ Just like that, and I was like, “Yeah, I mean, you’re way better than anybody I’ve ever seen.”

Tatum and the Celtics open the NBA Eastern Conference Final against the Miami Heat on Wednesday. Tkachuk and the Panthers open the NHL Eastern Conference Final against the Carolina Hurricanes on Thursday.