"He's still being evaluated, and his status is to be determined," Creighton sports information director Rob Anderson said. "Possible meniscus, but we'll take a look when we get back."
Earlier in the first half, Watson was helped off the floor after he collided with a Xavier player. Creighton's training staff iced his left knee, and the senior returned to the game.
Shortly thereafter, Watson landed awkwardly on a layup attempt. He screamed and clutched his left knee before being carried off the court for the second time.
After the game, Watson said he felt a pop the second time he left the court.
"When I went to go test it, there was no structural ligament damage, which is a good sign," Watson said. "But right now I gotta just live in that training room and try to get back for my team."
Watson, who transferred to Creighton after his sophomore season at Boston University, has averaged 13.4 points per game and connected on 48 percent of his 3-point attempts this season.
The point guard is the catalyst of a Bluejays squad competing for the Big East title.
Creighton went on to win the game 72-67 without its star guard, handing Xavier its third straight loss.