He tore the Celta Vigo left flank to shreds and helped the hosts find the back of the net with their first three shots on target of the match.
Celta Vigo picked up one back through a mistake by Barcelona goalkeeper Marc-Andre ter Stegen Down 3-0 early in the second half.
Having taken a blow to the head moments earlier, there was a scary moment on the hour mark as Ronald Araujo went down off the ball.
He required immediate medical attention as players from both teams frantically waived for medical personnel, and later he was transported to the hospital.