It’s a tough question because it’s situational.
In general, I expect us to try Grant, who might be successful for the same reasons that Semi was - and who has some advantages Semi does not. He’s more familiar with play near the basket, and honestly he’s just better.
I also think Horford is going to get stints. For a limited number of possessions, at the end of the game, it would not surprise me at all if Smart draws the assignment. We’ve seen him do an amazing job, but it takes an expenditure of energy he couldn’t sustain throughout the game.
Rob might be able to handle him, but I think he might have trouble with Giannis’ speed and sudden changes of pace and direction. Also, as we know, he’s established his value in an off-ball roaming helper role. I see him being guarded by Grant or Al, who are moving their feet to stay in front, and they’re getting help from other defenders who show. Then, as he’s working to find a way through that mess, he has to worry about Rob swooping in from behind or the side to block his shot.