St Mirren will find and ban the fan who threw a missile at Rangers striker Alfredo Moreles during the Ibrox club's win in Paisley Saturday, says chief executive Tony Fitzpatrick.
The Colombian appeared to be hit by an object as he celebrated a stoppage-time goal for the visitors.
It comes four days after Hibernian boss Neil Lennon was struck by a coin throw from the crowd at Tynecastle.
"It's unacceptable and we will find out [who did it]," Fitzpatrick said.
Speaking to BBC Scotland, he added: "The ground is full of CCTV. He will be banned. We don't want people like that at the games.
"But what can we do? We can impose a ban but we can't stop it, that's not the club's responsibility."
Rangers manager Steven Gerrard called for a lifetime ban, asking: "Is it going to have to take someone's eye to come out or someone to be badly hurt from an object for us to make it stop?
"These people shouldn't be at a football match. You just ban them forever. It's that simple. Then it will stop."