LAS VEGAS — Jayson Tatum broke into a little dance this week as he walked off the practice court at UNLV’s Mendenhall Center, heading in the direction of Boston Celtics teammate Jaylen Brown. Tatum lifted his hand, whirled it around, then swung his arm and bopped, side to side, letting Brown know that he can Milly Rock on any block. Brown chuckled as Tatum approached and did the same dance, only with his own elaborate improvisations.



No dance-off ensued, however, as the newcomer Kemba Walker and the team’s longest-tenured vet, Marcus Smart, converged on Tatum and Brown to chat. Photographers gathered around the quartet, lifting their cameras and leading to an impromptu photoshoot that amused Houston Rockets forward P.J. Tucker.



“Awwww, ain’t that cute,” Tucker said loudly as he sat along a wall, causing Walker to burst out in laughter.



The members of Team Shamrock — which Smart has dubbed the four Celtics vying for...