Jay-Z may be a Brooklyn native, but he was seen showin' love to the Boston Celtics after their wild comeback win over the Warriors -- dapping up Jayson Tatum after the game.
If you missed Game 1 of the NBA Finals on Thursday, the Celtics were down 12 points by the end of the 3rd quarter against Golden State ... but Tatum and the C's went off in the 4th and outscored the Warriors 40-16 -- pulling off an upset win, 120-108.
The Celtics did it all right on the Warriors' homecourt -- and hip-hop legend Jay-Z was front and center to watch the epic win at the Chase Center.
HOV had to show the Celts some love for their stunning performance ... and dapped up Tatum -- the Eastern Conference Finals MVP -- right on the court.
The cool part about the exchange? Jay-Z's track "On To The Next One," featuring Swizz Beatz, was playing on the arena's speakers.
Shawn Carter wasn't the only celeb in the crowd who witnessed Celtics' upturn ... San Francisco Giants legend Barry Bonds was also in attendance, as was legendary director Spike Lee.
Lee -- who's a diehard New York Knicks fan -- was seen on camera before the game giving love to Warriors star Draymond Green and yelling, "Let's go, baby! Let's go!"
FYI, Tatum had 12 points and 13 assists in the game ... but Al Horford was the star of the show, leading the team with 26 points.
Game 2 is slated for Sunday.