A fan at a Seattle Mariners game left the ballpark this weekend with a gnarly gash on his forehead … after he took two HUGE punches to the face during a fight in the stands.

The wild scene was all captured on video during the Mariners’ game Friday night against the Oakland A’s … when two fans got into an argument that turned violent.

In the footage, you can see the two were quarreling … when the man in a Mariners jersey suddenly unloaded a massive right to the other guy’s face.

The force of the blow was so vicious, it knocked off the guy’s hat and sunglasses.

The fighting, though, didn’t stop there … ’cause just a few seconds later, the same man unloaded a second right that connected flush with the other guy’s face again.

Somehow, the dude was not knocked down nor knocked out … though he posted on social media Saturday revealing the two punches left him with a bloody wound above his eye.

Fortunately, he didn’t seem to have too serious of injuries … saying on his Twitter page, “I’m fine btw! Ate them up.”

We’ve reached out to law enforcement to see if any arrests were made, but so far, no word back yet.

As for the game that night, the Mariners went on to win the tilt, 4-3.