The Celtics had two head coaches present at Saturday morning’s practice. One, of course, was Joe Mazzulla. The other: Mazzulla’s new Patriots counterpart, Mike Vrabel.

Boston Celtics coach Joe Mazzulla has shown up at New England Patriots practices in the past. So he extended an open invitation to newly-hired Patriots head coach Mike Vrabel to do the same at the Celtics’ practice on Saturday. Vrabel reportedly accepted and showed up at the practice.

After the practice, Joe Mazzulla spoke to the media about what it meant to have Vrabel at practice. “The four people that have these jobs for however long they have it, there’