NHL forward Jujhar Khaira was knocked out after taking a violent punch during a fight Monday -- and the blow was so vicious, the Oilers player had to leave the game due to injury.
The scrap went down in the 1st period of Edmonton's clash with Calgary ... shortly after Khaira infuriated Flames players by checking Oliver Kylington in the head with his shoulder.
Calgary forward Brett Ritchie hunted Khaira down, got him to drop the gloves for a fight, and then socked him right in the face.