The Boston Celtics played without Al Horford in Game 1 as he entered COVID-19 protocols.

According to ESPN's Brian Windhorst, there have been members of Boston's staff that have tested positive for COVID-19 in recent days.

"Al Horford was at shootaround [Tuesday] morning, so this is something that hit the team very much by surprise as they were getting ready to leave their hotel for Game 1," said Windhorst.

"This is the third time this season that Al Horford has been in health and safety protocols. It happened once in the preseason. He was out for five games in December.  And now he's out here.

"The NBA rules are a little complicated here. He can potentially be out a minimum of five days, which would be three games. He could also test out depending on whether he's positive or negative, or whether his viral load can be reduced. But it is unknown at this point whether that can happen.

"I will say, there are several staff members of the Celtics who have tested positive over the last few days. This is something that has got to be worrisome around the Celtics right now."