Emotional Derek McInnes revealed he wrote an apology letter to West Ham star George Parris after being left sickened by an act of racism from football fans in the 1980s.
The former Aberdeen boss was attending a match between the Hammers and his hometown St Mirren as a teenager but the contest was blighted by flashpoint from the stands.
McInnes - speaking in his Mail On Sunday column - called upon the incident ahead Rangers ' visit to Sparta Prague in the Europa League this week.
The clash is the first time the Ibrox side will face a team from the Czech Republic since Glen Kamara was racially abused by Slavia's Ondrej Kudela in last season's competition.
Football was sickened by the abuse as McInnes saluted the Finland's international ability to deal with the vile incident.
And the 50-year-old has explained the experience he encountered in his youth is what continues to fuel his desire to help rid the beautiful game of racism.
He said: "The first time I witnessed racist abuse was when I was 15 years old and I went to watch St Mirren play West Ham in a pre-season friendly in 1986.
"I'm from Paisley and West Ham's full-back George Parris was racially abused by several members of the crowd.
"I didn't receive a reply but I felt compelled to write a letter to Parris to tell him how disgusted I was about the abuse. Paisley is a good town and not everybody acts like those who abused him. I was hugely embarrassed.
"We've made massive strides but, after all these years, players are still being abused and that leaves a bad taste. When abuse is so obvious on the pitch, it's toe curling. It shows there's still a lot of work to be done on the situation."
