The English defender was told by his Liverpool manager he could not play, but play he did for Manchester United and arch rivals, City.
The player who proved the great Bill Shankly was wrong
The last time Manchester United and Manchester City met in the third round of the FA Cup, Sir Alex Ferguson had just taken the Old Trafford job, Margaret Thatcher was the British prime minister and a ticket on the Stretford End terrace cost £2.80 (Dh16).
United and City were not top of the table in January 1987, far from it. The Manchester clubs were not even in the top half of the table where teams like Luton Town, Coventry City and Wimbledon jostled for position.
City were 16th, United 13th and both teams looked to the FA Cup as their salvation from a dire season.
"We'd hoped for an easier draw than United," said John Gidman, City full-back, who had moved across Manchester the previous year. "We were having a hard time of it and hadn't won a single away game in the league from the 12 we'd played."
Gidman had spent five years at Old Trafford and still socialised with many of his former teammates.
"The fans may have hated each other, but there were no problems between the players," said the Liverpool-born Gidman, now 57 and residing near Marbella on Spain's Costa del Sol since 1998.
"The City and United lads lived in the same areas and would see each other socially. The banter was good, but the mood changed during the match."
United won a poor game 1-0 with a single Norman Whiteside goal, but City were angered when Imre Varadi scored with a header, only for the goal to be disallowed for a questionable push.
"One decision has cost us a lot of money," Jimmy Frizzell, the City manager, said.
"We felt cheated," said Gidman, "felt that we deserved a replay, but big Norman took his goal well."
Gidman knew all about Whiteside. "I saw him join United's first team as a 16 year old and mature very, very quickly," he said. "Normally it takes a player three years, but Norman was the finished product within a year and had already been a star in the World Cup.
"He was so strong for a young lad, but it's wrong to call him a lad because he was a man at 16."
Ferguson was elated. Poor league form meant he was under immediate pressure after arriving from Aberdeen. The cup win bought respite and unprecedented demands for interviews.
"Just how many radio stations are there in Manchester?" he said following another post-match request.
Gidman never played under Ferguson. He left United for City with some reluctance in February 1986.
"United bought another full-back and I didn't want to play reserve football. The manager Ron Atkinson was reasonable, offering to pay up my contract and give me a free transfer. I also had to sign a form stating that I would keep quiet about certain things that had happened at the club. Atko [Atkinson] and I shook hands and we left on good terms."
Gidman also said his goodbyes to his teammates. "I had bought a sports shop in Liverpool and honestly thought that I was going to run that for the rest of my life."
Then he received a phone call from Frizzell that very day.
"Frizzell wanted to sign me. He said, 'We're playing United on Saturday and I want you to play.' So I signed and I marked Peter Barnes. He told me to go easy, but you can't do that. He was a great lad but a bit of a softy and I said: 'I'm going to kick you for 90 minutes.' They took him off after 40.
"I had two good years at City but I didn't see eye to eye with the new manager Mel Machin. I swear he couldn't coach a parrot to speak."
Machin had a higher opinion of Gidman and made him club captain. "He used that to try and get me to deliver difficult news to the lads. Once, after playing Bournemouth, the lads had been offered a night out if we won.
"We duly did, and then Machin changed his mind and told me that I had to tell them that they couldn't go out. We went back to the hotel and I told the lads to order drinks on his room bill. He found out and got the hump. We had a bust-up, not quite fisticuffs. He stopped talking to me and I was let go.
"It was weird playing at Maine Road [City's former home ground]," he said. "Old Trafford always seemed full, yet there were gaps at Maine Road. But City fans were fabulous to me."
Gidman was, by then, at the tail-end of a fine career.
"I grew up in one of the poorest areas of Liverpool and joined Liverpool FC as a kid until Bill Shankly told me I wasn't good enough," he said. "He said that I wasn't skilful enough and wasn't the right build. I cried all the way home on the bus after hearing that because I thought I'd never be a footballer and spent most of my career trying to prove him wrong.
"I played for Aston Villa, Everton, Manchester United, City and Stoke. I also played for England. So Shankly was wrong, because I was good enough."
Gidman's career kicked off at Villa, where he became a crowd favourite alongside Andy Gray, who remains his best friend. He overcame a career-threatening injury caused by a firework going into his eye, before being called up for his country in 1977.
"Hearing the national anthem before the game did it for me and I became very emotional," he said. "Then I just thought, 'I hope you are watching this Bill Shankly, I really do because you let me go for nothing and now I'm playing for England."
Big money moves to Everton in 1979 and Manchester United in 1981 allowed Gidman to put money into a pension which has served him well to this day.
Gidman's decision to move to Spain was made on holiday in Cuba, where, he acknowledges, his "head was everywhere".
After leaving Manchester in 1988, his life underwent more twists and turns than he ever had to encounter marking players like Kevin Sheedy and Glenn Hoddle. He had been close to jail after a Liverpool golf venture attracted the attention of the police and saw his telephone bugged, he had a gun pulled on him and went through a messy divorce. Liverpool was not a good place for Gidman to be.
"Cuba turned out to be the best holiday of my life," he said. "I went with a mate for six weeks and it allowed me to get my head together because I got away from everybody. I'd fallen in with the wrong crowd and I needed to make a break.
"With two days of the holiday left I sat alone looking out to sea, just thinking. I thought, 'This is where it started for me, by the docks in Liverpool, by the sea. I wanted to get back to the sea. I decided that I didn't need anybody in my life and that I was going to live in Spain. My mates thought I was mad."
Gidman was adamant, however.
The memory of Liverpool took him back to a time when life was simpler and he needed that again.
A friend in Liverpool offered to help out.
"He knew a lad in the Costa del Sol who knew the area so I ended up near Malaga and I've been here ever since. I met my girlfriend 13 months after arriving. She caught my eye on the beach and while I didn't speak Spanish, I just took a couple of drinks over and said, 'For you, for me.' She told me she was married, but that relationship was breaking down and we got together soon after. She's an air stewardess and we get on. I'm happy after years of madness."
He'll watch Sunday's game on television. "I think City are clear favourites," he said. "They destroyed United 6-1 last time. United have injuries and a far weaker squad."