INDEPENDENCE, Ohio _ When cousins Tyronn Lue and Justin Tatum got together every summer, part of their chatter centered around "Little J."
But even though Justin's son, Jayson, had NBA dreams at an early age, the two men's predictions for the boy's future _ at least until he reached 14 or 15 _ were more braggadocio than reality.
"There was all kind of street talk basketball talk," Justin Tatum said. "That was a vision of Jayson's for a long time. Ty was part of the game, he saw things that if Jayson worked on, that dream can come true.
"Obviously we never imagined or fathomed this pace or this level right now. We felt that in this day and age, what basketball is becoming, if Jayson stuck to it he could achieve that goal. It was just family jibber-jabber here and there."
What they never imagined comes to fruition on a grand stage Sunday afternoon at TD Garden. Lue will coach the Cavaliers against rookie of the year candidate Tatum and the Boston Celtics in Game 1 of the Eastern Conference finals.
A 6-foot-8, 205-pound small forward who was the third overall pick in the 2017 draft, Tatum has been sensational in his debut season, averaging 13.9 points, 5.0 rebounds and 1.6 assists. In the playoffs, he's leading the Celtics with an 18.8 average and has scored 20 or more points in eight of their last nine games.
"Seeing Little J when he was six or seven years old to who he is today is crazy," Lue said Thursday. "Seeing the player he's become, we knew he was going to be good, but now he's at a whole new level."
Justin Tatum's late uncle was Lue's beloved grandfather Tyrone George, who was born on the Fourth of July. Tatum played college basketball at St. Louis University and still lives in that city, where he coaches the boys team at Christian Brothers College High School. For years, Tatum said he drove the two hours to Mexico, Mo., for the family's annual Fourth of July celebration. Early into Lue's 11-year NBA career, Lue began footing the bill for the town's day-long bash, complete with fireworks, a blues band, and a pool party for the kids.
Lue, 41, said Tatum, 39, often brings his best friend, Larry Hughes, a St. Louis U. product who played 13 seasons in the NBA, including 2 { seasons with the Cavs starting in 2005.
"I've known T-Lue my whole life," Tatum said by phone Friday from St. Louis. "It's been a family tradition even before he put his stamp on it with his Fourth of July weekend. It's been something we've done every year for decades. It became even bigger since he became the coach of the Cleveland Cavaliers. "
Jayson Tatum, 20, started attending the barbeques when he was 5 or 6, Lue said. But Justin Tatum said Lue never discussed the possibility of an NBA career with Jayson.
"He never got a chance to have personal conversations," Justin Tatum said. "He just knew that Ty was a family member who was in the NBA, with his size what he had to do, and played for the Lakers. So when he did see him play on TV, he had the relationship part of it.
"It wasn't just that Ty Lue made it to the NBA, that Jayson felt he was going to get advice and all that. It was another example of a family member that gave him a dream of what he could accomplish."
Cavs star LeBron James also knows Justin and Jayson Tatum because of the Hughes connection.
"His dad used to bring him around when I used to play with Larry Hughes," James said Friday. "I remember actually being on the floor with him one day. I'm not going to sit here and say, 'You could see he was going to be a pro,' how those corny stories come out. He was just happy to be around NBA guys and he wanted to play ball.
"I've watched him ever since he entered the high school ranks. As dominant as he was in high school and going to Duke and being dominant in the year he was there, he's showcasing what he's able to do at this level, too.
"More than his game, he's a great kid. I know his dad more than I actually know Jayson. His dad is a standup guy as well and he comes from a great family. The game speaks for itself."
Lue has been impressed with how Jayson Tatum has performed as a rookie, especially since the Celtics are without All-Stars Gordon Hayward, who played only five minutes of the opener against the Cavs before dislocating his left ankle and fracturing his tibia, and Kyrie Irving, who underwent surgeries on his left knee on March 24 and April 7.
"I think his toughness," Lue said of what's helped Jayson Tatum stand out. "He's not scared ... and he's always been that type of kid. He wants these types of moments. With Kyrie and Gordon going down and having a chance to play the minutes he's been playing, starting and playing in the playoffs the way he has, he's taken full advantage of it. But he's never been afraid of the big moment. You can see that."
Asked how tough it is to coach against family, Lue said, "It's tough because you want to see him do well, but not against you."
Justin Tatum tried to ease the postseason pressure on his son with his recent advice.
"He's doing well right now. He has a big task ahead of him," Tatum said. "I just want him to enjoy the moment and understand, 'You prepared yourself for situations like this, no matter if it came two years into your career or your first year. Just come out here and give it your all. Nobody can blame you for not beating LeBron if you don't beat him and you can get nothing but praises if you do. It's in your favor either way.'?"
Lue said he recently looked at pictures of Jayson when he was little and it struck him as "kind of weird" to be facing him in the playoffs. That feeling is mutual, at least for Justin Tatum.
"I texted him the other day, 'Would you ever imagine this game being played?'?" Tatum said. "He sent me an LOL back: 'I can't believe it.' Especially this early in his career and he's not just on the team, he's doing a lot for the team's success. To be going against T-Lue, it will be good to have family laughs and stuff like that."
