Garza was inserted into Boston's starting lineup against Philadelphia on Saturday after Jayson Tatum was sidelined, but played only the first six minutes before leaving with two quick personal fouls.
Coach Joe Mazzulla's decision was a surprise in a winner-take-all playoff game, given Garza had never previously started an NBA playoff contest.
The former Iowa center started six regular-season games this season and 11 across his five-year NBA career, making the move a notable sign of Boston's trust in him.
Was starting Luka Garza in Game 7 a desperate gamble or a calculated masterpiece by the Celtics' coaching staff?
With their superstar sidelined, did the Celtics' surprise lineup reveal a fatal flaw or a hidden strength?