No, it's not another Celtics injury but rather a clear-as-day indication that Horford left all he had to offer on the court today, enough to help Boston escape with a 113-107 overtime win against the Milwaukee Bucks.
Boston now leads the best-of-seven series 1-0 with Game 2 at the TD Garden on Tuesday.
As for Horford, he would lead the Celtics with a double-double that included a team-high 24 points to go along with 12 rebounds, four assists, two steals and three blocked shots.
Making the performance by Horford even more impressive offensively is that the bulk of his points came from the free throw line where he was 13-for-14, damn near doubling up his previous playoff career-high for free throws made (7) and attempted (8).
"We were trying to get me in post-up situations," Horford said. "They did a good job fronting and making it difficult for me to get the ball and the way that they were playing me, it's forcing me to be closer to the basket, which is fine with me. I'm just trying to find ways to be efficient and help the team."
Said Celtics coach Brad Stevens: "We're going to ride Al. It's just … he's been unbelievable in being a facilitator for us all year. He has his moments because of the way that we're being defended, where he gets to be more of a featured scorer. With where we are now, he's going to be more of a featured scorer, and facilitate, and guard Giannis (Antetokounmpo), and do everything … he'll probably run our film session tomorrow. So that's … that's his job."
Indeed, Horford's greatest strength since he signed with the Celtics in the summer of 2016, has been his versatility to impact the game in a multitude of ways at both ends of the floor.
And this time of year, that means Boston will lean even more on the five-time all-star than usual.
That was certainly the case on Sunday with Horford playing more than 44 minutes – just two minutes less than his playoff career high in minutes played which occurred in 2012 when he played for the Atlanta Hawks and they faced the Boston Celtics.
Jaylen Brown, another member of the sore and slow-moving Celtics on Sunday following the win, recognized his elder teammate's slow gait as well.
"I know Al's body is killing him," said Brown who played a team-high 46 minutes. "he'll be alright. Everybody has to recover. Get some sleep, ice down and he'll be alright."