BOSTON -- Marcus Smart gutted out a painful right ankle injury in Saturday's Game 3, but he won't be able to do the same Monday night.
The Celtics have ruled Smart out for Game 4 of the Eastern Conference Finals against the Miami Heat at TD Garden. Derrick White will start in his place, per the team.
ESPN's Adrian Wojnarowski suggested earlier in the day that the Celtics weren't banking on Smart's availability.
Smart suffered the injury in the third quarter of Game 3 and had to be helped off the court by two trainers after writhing in pain on the floor. He made a dramatic return later in the quarter and even hit a 3-pointer to aid Boston's comeback attempt, but it's certainly possible he was running on adrenaline that helped him battle through the injury.
"It is quite swollen," Celtics coach Ime Udoka said Monday of Smart's ankle, noting the point guard would go through pregame testing to determine whether he'll play.
Report: Heat will be without key player in Game 4
Smart also missed Game 1 of this series (a 118-107 loss) due to a right mid-foot sprain and sat out Game 2 of the Celtics' series against the Milwaukee Bucks (a 109-86 win) due to a right quad contusion.
Smart's absence in Game 4 is a significant loss for Boston: The Defensive Player of the Year and NBA Hustle Award winner played a big role in the Celtics' only win of the series, tallying 24 points, nine rebounds and 12 assists in a Game 2 victory.
While big man Robert Williams is expected to return for Game 4 after missing Game 3, Boston will need point guards Derrick White and Payton Pritchard (three points combined on 1 of 3 shooting in Game 3) to step up if they want to even the series at 2-2.
NBC Sports Boston's coverage of Game 4 begins at 7:30 p.m. ET with "Celtics Pregame Live," with tipoff set for 8:30 p.m. ET.