The 28-year-old claimed he was grabbed by the neck and suffered a cut above his eye following an incident involving Sale Sharks England forward Jonny Hill following Bath's Gallagher Premiership play-off win.
Hill, who is currently recovering from an injury and has not played since January, watched the game with Sale's coaching team from the main stands at the Recreation Ground.
The 6ft 7in Hill was involved with the man as he left and walked down the stairs after the final whistle, which Sale lost 31-23.
A Bath supporter, who wished to remain unnamed, told reporters: “I was sitting there, and he came down the stairs, grabbed me by the neck, broke my sunglasses and cut the top of his eye.”
“He told me, 'Don't ever do that again.'
“Honestly, all I want is a new pair of sunglasses. I don’t want to make a big deal out of it.
“I was sitting with my partner and her family. This is not football.”
Sale released a statement confirming that it was investigating the allegations.
“Sale Sharks are aware of an incident involving a player and a Bath Rugby fan during the final whistle of today’s semi-final,” the club said in a statement.
“The club will be working with Bath Rugby to complete its investigation into the incident and will not be making any further comment at this time.”
Asked about the incident at the post-match press conference, Sale Rugby manager Alex Sanderson had no knowledge of the incident.
“This is news to me,” Sanderson said. “Johnny is not the aggressive type, so I will answer those questions to the best of my ability.
“I can vouch for Johnny’s personality. He is not an overly aggressive and malicious person.”
