Celtic boss Brendan Rodgers has stressed the need for safety at stadiums after Hibernian manager Neil Lennon was felled by a coin in the Edinburgh derby.
Former Parkhead manager and midfielder Lennon was struck on the jaw in the 0-0 draw at Tynecastle on Wednesday night, moments after Hearts had a stoppage time goal disallowed.
Jambos keeper Zdenek Zlamal claimed he was punched by a fan while both assistant referees Frank Connor and David McGeachie were also struck by objects.
Rodgers, named Premiership manager of the month for October, voiced his concerns over the incidents. Speaking ahead of today's visit by leaders Hearts, he said: "I've seen some of the images on it. It's not nice when you see a fellow manager get hit by a coin.
"The passion for football here is fantastic. You go to these grounds and there's a real intense atmosphere at a lot of them, but it can never spill over.
"To see the actions of both sets of supporters was disappointing.
''There has to be a safe environment, whether you are a player or manager, for you to go and do your work.
"The respective clubs have come out with their statement, which shows their togetherness on it, and hopefully it won't happen again.
"I get quite a bit of abuse as well but my focus is very much on the game. That's not right or wrong. It's just my way, other managers are different.
"But ultimately you have to be able to work without the threat of being hit with a coin or a punch."
Lennon backed his agent Martin Reilly's claim that he is routinely targeted for abuse in Scotland because he is an Irish Catholic who played for Celtic.
Rodgers, himself a Catholic from Northern Ireland, said: "It's not something I really want to go into. I can understand what Martin is saying.
"But whatever your religion is, you shouldn't be subject to that.
"I've been up here two-and-a-half years and it's been a brilliant place to work and live.
"There's really authentic people here, very passionate about the game. I've loved my life here.
"But it can't overstep the mark. You come onto a football pitch, you're in to do a professional job, you want the intensity, the passion, but you have to be protected as a player and a manager."
Celtic beat Hearts 3-0 in the Betfred Cup semi-final last Sunday and can go within a point of the Jambos with a win today.