The Boston Celtics were outplayed by the Miami Heat in Game 1 of the Eastern Conference Finals on Tuesday, losing 118-107 in South Beach. But, it didn't help that Marcus Smart and Al Horford both didn't suit up.

Smart will likely return for Game 2 after sustaining a foot injury, which is huge for the Celtics defense. However, Horford remains in health and safety protocols and is unlikely to play, unless he somehow gets cleared before tip-off.

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Via Tim Bontemps:

Horford only got vaccinated recently and was put in protocols prior to the series opener. He's proven to be a key piece of this Celtics group during their playoff run, averaging 13 points, 9.4 rebounds, and 3.4 assists on a 45% clip from downtown. The big man has also provided stout frontcourt defense.

While he did struggle offensively in the final three games of the Bucks series, Horford showed out before that, even going off for 30 points in Game 4 vs. Milwaukee. The Celtics could surely use him right now, especially with how Jimmy Butler is playing.

Boston is set to be without Derrick White as well on Thursday because his wife is giving birth to their newborn child. The Big 3 of Jayson Tatum, Jaylen Brown, and DPOY Marcus Smart will all need to ball out in Game 2.