The Boston Celtics are coming off a thrilling victory over the Detroit Pistons, but they sustained an injury to one of their key starters. According to Brian Robb of the Boston Sports Journal, Marcus Smart has been ruled out for Monday night's game versus the Toronto Raptors due to a thumb injury.

Smart suffered the thumb injury late in Sunday's narrow win over the Pistons. The Celtics took down the lowly Pistons with a game-winning shot by Jayson Tatum with three seconds remaining, leaving Detroit with little time to conjure up a shot.

Following Boston's latest victory, the team originally listed Smart as questionable to play on Monday. However, Robb reported that the Celtics are taking a cautious approach with Smart's thumb ailment due to it being the same thumb that he injured a couple of years ago.

With Jeff Teague also out and Kemba Walker missing time to begin the season, the Celtics have instilled confidence in Smart to be in the starting lineup. As a result, in the first seven games in the season, Smart has played a career-high 33.1 minutes per game for Boston.

In those seven games, Smart has recorded 12.6 points, 2.3 rebounds, a career-best 6.7 assists, and 1.6 steals per game. But without him on the court, the Celtics will likely lean on Tatum and Jaylen Brown—who is tied for fifth in scoring in the NBA right now—a bit more against the Raptors.

At the same time, the Celtics will likely deploy more of rookie Payton Pritchard, who played a season-high 27 minutes on Sunday versus Detroit.