The Cougars beat the visiting Washington Huskies by a field goal in overtime in front of 30,000 fans Friday night. As you can see at around the :13 mark on the 45 yard line in the video above, the overtime win was apparently not enough for one fan who was out for blood.
According to CougCenter, the man in white (you can sort of see he is also holding his helmet) is Washington tight end, Austin Seferian-Jenkins as he walks off the field following the overtime loss. A fan rushing the field comes out of nowhere and sucker punches Seferian-Jenkins, leveling him to the ground, and is gone as quickly as he appeared.
Seferian-Jenkins had initially tweeted that he "prayed for that man that struck me. He must have some issues..." but appears to have since deleted the tweet (though he has acknowledged the punch in other tweets). According to The Seattle Times, Washington will not have any comment on the incident.
Apple Cup 2012: Washington player punched as fans rush field [CougCenter]
Washington TE Austin Seferian-Jenkins struck by fan [USA Today]
Seferian-Jenkins hit by fan after Apple Cup [Seattle Times]