Boston Celtics star Gordon Hayward has entered the NBA's concussion protocol and is listed as doubtful for Monday's game against the Denver Nuggets, the team announced on Sunday.
The 28-year-old left Saturday's contest against the Atlanta Hawks after making contact with John Collins on a screen.
Hayward has had an up-and-down second season with the Celtics, averaging 10.8 points, 4.3 boards, and 3.4 assists. He missed all but one game last year after suffering a fractured tibia and dislocated ankle in the season opener.
