“It reminds me of the process that I used to go through to get ready for the season,” Pierce told Kevin Garnett of working out with Tatum over the summer. “Just being able to watch him, and seeing him do the things that make him great — it’s an honor.

“He’s one of the top five players in the league, so it’s an honor to be there and see him go through his journey to see him get ready. I’m there really on some support, just to see his growth. He’s already at the top of the food chain, so I’m just part of being a support system.”

According to Pierce, it was his former Celtics teammate — and current Boston assistant coach — in Sam Cassell who encouraged both he and Tatum to begin their offseason reps together. 

“Really, I went with Sam to watch his workout. So kind of Sam [initiated it],” Pierce said, as transcribed by Chris Forsberg on NBC Sports Boston. “With that whole thing, with me and him, I’m just here for support. And it’s getting me back in shape.”

Tatum has regularly praised Pierce for his accomplishments on the parquet floor, even though he was a Kobe Bryant fan growing up.

In an interview with NBA writer and insider Jeff Goodman earlier this month, Tatum listed Pierce among the greatest to ever play for the Celtics — noting that he wants to join such rare company as he continues his own playing career.

“I would love to be on the Mount Rushmore of Celtics,” Tatum told Goodman. “Bird, Russell, Paul Pierce and those guys. They paved the way. The one thing all those guys have is chips. I have to get to the top of the mountain to even be considered as one of those guys. I want to be an all-time great, I want to be known as a winner, and I believe I will be.”

Even though Tatum is arguably one of the best pure scorers in the game today, former Celtics guard Tony Allen believes that the 25-year-old forward can still learn plenty from Pierce as he looks to lead Boston to that elusive 18th championship. 

“That seek and destroy mentality,” Allen, also a guest on “KG Certified”, said of what Tatum can gain from Pierce. “I ain’t saying Tatum don’t got it, but [Pierce is] working out with him. I think that’s good insight. I think that goes a long way, (rather) than just being around some random trainer telling you to, ‘Step back, step back.’ I think it’s all about mentality when you get that rock.”