On Wednesday, Chris Forsberg of ESPN.com passed along comments from Pierce about the potential for the No. 5 to join his No. 34 in being immortalized at TD Garden.
"Without a doubt, KG's number will be [the next one] retired in Boston," he said. "It's going to happen."
Celtics President of Basketball Operations Danny Ainge confirmed the franchise has discussed adding Garnett to the rafters and downplayed concerns about the power forward's limited time with the team, per Forsberg.
"It was six years of potential championship-caliber teams and All-Star play from KG," Ainge said. "I think that it was a pretty significant impact he had in those six years."
Garnett and shooting guard Ray Allen joined Pierce, who'd already been on the Celtics for nine years, in 2007 to instantly transform the team into a championship contender.
The South Carolina native spent the first 12 years of his career with the Minnesota Timberwolves, with whom he was named the NBA's Most Valuable Player for the 2003-04 season.
While he wasn't quite as dominant in Boston, he still averaged 15.7 points, 8.3 rebounds and 2.7 assists across 396 regular-season games with the organization. More importantly, he helped end the team's 22-year championship drought in 2008.
Pierce went on to tell Forsberg that Garnett could have his jersey retired by the Celtics before it happens with the T-Wolves due to lingering tensions with ownership.
"[Garnett would] rather have his jersey retired in Boston than in Minnesota," he said. "He'll eventually have his number retired with the Timberwolves, too, but he'll have to wait until management sells the team."
If Pierce's prediction comes true, Garnett will join the likes of Bill Russell (No. 6), John Havlicek (No. 17), Kevin McHale (No. 32) and Larry Bird (No. 33) with their number retired by the Celts.