Replays showed Colombia's Juan Camillo Zuniga kneeing Neymar in the back while challenging for the ball. It happened in the 87th minute.
Neymar has four goals in the World Cup and is Brazil's leading scorer.
Early reports indicate that Neymar has gone to hospital for further examination.
He has been playing with a knee and thigh injury after a rough match in the Round of 16 against Chile.
Brazil won Friday's quarter-final match 2-1 and moves on to the semifinals to face Germany on July 8 in Belo Horizonte.