Former Celtic player Nir Bitton says the rivalry between Glasgow’s big two brings about a “hatred” that can’t be found in any other sporting contest.
He says the game is so overwhelming that he was left in tears and refused to leave the house when he was on the losing side.
The Israel international left Parkhead for the last time earlier this month after helping the club lift the eighth league title from his nine years in Scotland.
The 30-year-old also won four Scottish Cups and six League Cups after signing for Celtic in 2013.
In an interview in his home country he revealed that tensions run so high on derby day in Glasgow that the winners could “run the city’s streets naked” after the game while the losers have to “stay home and cover themselves with all the blankets they can”.
And the games means so much to players that he admits he was left in tears and refused to leave the house following a sending off at Ibrox in a 1-0 defeat that caused thousands of supporters to bombard his social media pages.
Speaking to Israeli channel Sport 1, he said: “Rangers-Celtic is something I cannot even explain in words.
“It’s a hatred I’ve never encountered in terms of football and sports.
“In Old Firm week, if you win you can go naked in the city, if you lose you better stay home, cover yourself with all the blankets you can and disconnect from social media.
“Last year when I got the red at Ibrox, it was the hardest time of my life. I have never faced such a difficulty in my life.
“There were thousands of posts, I stopped counting, I stopped logging on to Instagram. I would find myself lying in bed crying.
“I said ‘How did I get here?’ It was not an easy time, when my wife wanted us to go shopping I would tell her ‘sorry, I’m not leaving the house’.”
Bitton was also left crying at Celtic Park on the day of his final game at home to Motherwell, only this time it was tears of happiness and pride as him and Tom Rogic were given a farewell to remember by 60,000 fans.
He said: “The week before the official announcement of departure was very difficult for me. I cried a lot. I would see videos and the tears would come out.
“This is a club where I spent my whole career, I went through everything there: victories, sad moments, injuries, titles.
“I saw my whole career pass before my eyes in a few moments. In the last game, which was also a coronation game, I sat on the bench before the players came up, there was an exciting atmosphere.
“And when the Celtic crowd sang You’ll Never Walk Alone with the scarves in the air I cried and I could not control it. I owe a lot to Celtic for the trust and everything they have given me in my career and life.”
He is now looking forward to a different challenge after a decade of success in Glasgow.
He said: “I won everything there, I played in all the possible stadiums against the biggest players and I want to experience something different, whether it is abroad or in Israel.”