Giannis Antetokounmpo Puts Celtics On Notice With Bold Christmas Day Prediction originally appeared on NESN. The Boston Celtics and Miami Heat will renew their rivalry on Christmas Day, but Giannis Antetokounmpo apparently has no intention of waiting until December to make his prediction. The Heat and Celtics have plenty of history, and Miami's acquisition of the two-time NBA MVP added another fascinating layer to the rivalry. MORE: Celtics Handed Immediate Test In NBA Season OpenerAdvertisementAdvertisement AdvertisementCeltics Receive Early Christmas ChallengeAntetokounmpo's prediction carries no actual consequences in August. By promising to "put on a show" and earn a win, Antetokounmpo created a clear expectation for his first Christmas appearance with Miami.