Professional Footballers' Association chief executive Gordon Taylor has called for crowd control netting to protect players following trouble in Sunday's Manchester derby.
Manchester United's Rio Ferdinand was hit by a coin as he celebrated his side's late 3-2 win, while City goalkeeper Joe Hart had to step in to stop a man who ran onto the pitch towards the defender.
Taylor, speaking to Sky Sports News, said protective netting should now be a focus.
"It could have been a very serious injury to Rio Ferdinand so I think it's a real wake-up call to the football authorities, to the safety officers at grounds working with police and clubs, to try and prevent that happening," Taylor said.
"One option that's been talked about is netting in vulnerable areas: when a player's taking corners, behind the goal, or behind the managers' dugouts where the subsitutitions are.
"I think we've got to look at that seriously, so long as it doesn't affect vision, and of course nobody's talking about bringing fences back. Football is there to be enjoyed by the whole community."
Greater Manchester Police confirmed on Monday that nine people had been charged in connection with the unrest at the Etihad Stadium.
Among the charges faced are racially aggravated public order and pitch encroachment.
Police are still investigating the coin incident, which left Ferdinand with a bloodied face.
The incidents were condemned by both football clubs, as well as FA chairman David Bernstein.
"What's happened is totally unacceptable, deplorable," Bernstein told Sky Sports News.
"To see Rio Ferdinand with blood on his face is absolutely terrible. It's sad to see such a fantastic match followed by these headlines.
"It's disturbing that we're seeing a recurrence of these sorts of incidents. We've had some racial abuse incidents, pitch incursions, things being thrown at players.
"It's very unacceptable. It's for the FA, the whole game of football, the authorities to work together and deal with it in a most severe manner.
"It's a social problem. I think there's a copycat thing, so it's important to bring matters to a head. We will do everything we can to stop this blot on the game."