His visit was not purely ceremonial and also gave him an interesting perspective on the game.
"I was more of a coach because we play Boston Wednesday, so I was sitting there as a complete coach and scout," Rivers said Monday, when his Los Angeles Clippers won in Brooklyn. "But it still was really interesting to do that. I may have to do that more. It was really cool. I got a lot out of it, I really did."
The Clippers have won four of their last five games and are 4-2 since the mega deal that sent Blake Griffin to the Detroit Pistons, for a package that included former Celtic Avery Bradley, who makes his second return of the season to the TD Garden.
DeAndre Jordan, the big man and center of all kinds of rumors before the deadline, wasn't moved and had 16 points and 17 rebounds in Monday's victory that saw the visitors led by seven players in double figures.
"I think a lot of people slept on us when we got all these players but I think we're getting better and better," Los Angeles guard Austin Rivers said.
The Clippers are 12-5 in their last 17 games. They are 29-26 on the season, 2-1 on their current seven-game road trip.
They're going in the opposite direction of the Celtics, who were hammered by the Cleveland Cavaliers on Paul Pierce retirement night, their second loss in three days on their home floor.
Brad Stevens' team, once 16-2 after a 16-game winning streak, has gone 22-15 since reaching 18-3. At 40-18, they trail Toronto by one game for the division and conference leads.
Boston has missed the defensive intensity of Marcus Smart, who has been out after lacerating his right hand on a picture frame in an L.A. hotel room last month after missing a shot that would have beat the Lakers.
The next night, on the same Staples Center floor, Boston beat the Clippers.
"We've done it in practice," Stevens said. "We did it a couple weeks ago where Al and Gordon both had the grease board. I can't remember if I've ever done it like in the middle of a game where players go and draw it up. We haven't been up that much very often. We've talked about that stuff. I totally get where Steve would be coming from with that."
Said Horford: "I was wracking my brain trying to come with (plays). We needed to come up with certain plays and I was like, 'I have no idea.' Once you start putting everything together and seeing what makes sense and what doesn't make sense. Coach is -- he is a genius, man. He's pretty smart."
Speaking of Smart, he did some shooting after practice and appears to be on target to return to practice after the All-Star break.
The Celtics have taken the last two games against the Clippers at TD Garden.