In the fourth quarter against the New York Knicks, James Harden tried to drive into the Knicks' interior defense, but slipped into a turnover. As the ball got knocked away from him during a collision with Iman Shumpert and Tim Hardaway Jr., his head hit Shumpert and then Hardaway Jr.'s knee and elbow on his way down.
He left the game at the next stoppage in play. After going through some quick concussion tests, the Rockets' training staff deemed him OK to return to the floor. To this point, Harden has been a key part of Houston's offense, scoring 31 points on 15 shots with eight rebounds and a couple assists. He's also had a handful of turnovers, but his impact has especially been his ability to draw fouls and get to the free-throw line.
The Rockets had also lost Greg Smith to injury earlier in the game, who has not returned.