King County prosecutors contend William D. Van Meveren left the other man with nerve damage and a broken nose after punching the Vikings fan during the Nov. 4 game at Century Link Field.
According to charging papers, the 34-year-old Vikings fan had been watching the game with his wife and sharing good-natured taunts with other spectators for much of the game. As it drew to a close - a Seahawks win, as it happened - the couple got up from their seats to leave, hoping to beat traffic.
On the way out, the man shook hands with Seahawks fans when Van Meveren "sucker-punched" him in the face, a Seattle detective told the court. Knocked unconscious, the man tumbled down the stadium steps.
Witnesses to the punch identified Van Meveren, a 34-year-old Kent resident, as the assailant, according to charging papers. He was arrested shortly thereafter.
Offering an account unsupported by witness statements, Van Meveren claimed someone threw a punch at him shortly before he lashed out, the detective told the court.
"He did not report that the person he punched was the person who punched him, but said that he just punched the man in front of him," the detective continued.
The Vikings fan suffered a broken nose and nerve damage that caused him extensive pain in his arms and shoulders, according to charging papers. The man told police he still has occasional tingling in his hand due to injuries sustained in the attack.
Van Meveren has been charged with second-degree assault in the case. He has not been jailed.