Metta Sandiford-Artest just became a big Blake Griffin fan ... and it's all a result of the new Celtics forward's decision to rock #91 in honor of the great Hall of Famer, Dennis Rodman!!
TMZ Sports spoke with Metta out in Beverly Hills this week ... and he was pleasantly surprised to learn Griffin was paying respect to Rodman's legacy with his jersey number this season.
"That's incredible," the 2003-04 Defensive Player of the Year said about Griffin's number change.