"A 4-0 Hampden defeat by Celtic ended Sir Alex Ferguson's time at Rangers - this Ibrox team's careers are on the line"

Ferguson was blamed for the opening goal that Billy McNeill, who he had been deployed to mark by manager Davie White despite being a centre forward, headed home at a Bertie Auld corner in just the second minute and never played for the Ibrox club he had grown up supporting again.

Ronnie McKinnon - who played alongside his fellow Govanite in front of an astonishing crowd of 132,870, an all-time record for an Old Firm game, that afternoon - feels that several members of the current team could now suffer exactly the same fate.

Bruno Alves, Daniel Candeias, Graham Dorrans, Andy Halliday, Jason Holt, Russell Martin, Alfredo Morelos and Jamie Murphy have all been criticised for their lacklustre showings – while manager Graeme Murty has few backers left among the support following the pathetic capitulation of his charges.

McKinnon, now 77 and living outside Stornoway where he regularly watches Rangers matches on television at the Lewis and Harris Supporters Club, knows the game has moved on since his heyday, but he believes that suffering such an embarrassment will still have repercussions.

“I remember the Scottish Cup final game in 1969 well,” he said. “We had a game plan and part of it was to stop Billy McNeill from getting headers.

“It was normally my job to guard McNeill. It wasn’t easy because he was absolutely brilliant in the air. But our manager Dave White said he wanted Alex Ferguson to guard McNeill. At the team meeting before the game I said: ‘Look, it’s my job to mark him’. The manager said: ‘Not this time. Fergie’s good in the air’.

“When the first corner came in I was standing in the middle of the penalty box, where I had been told to position myself. But the ball sailed high over my head and there was McNeill at the far post by himself. He headed it into the net. That one goal knocked the stuffing out of us. We never recovered.

“Fergie never played for the Rangers first team again. I could sympathise with what happened to him. He was just as surprised as me that he was chosen to mark McNeill. Of course, he has gone on to become probably the greatest manager Scotland has ever produced.”

McKinnon added: “But you know when you play for Rangers against Celtic that your career is on the line. It is all hyped up to such an extent that if you make a mistake you might never play again. You know when you go out on the park that if you don’t play well it might be your last game.

“When you play against your greatest enemy you have to stand your ground. If you can’t do that then you shouldn’t be on the park. The players understand that if they don’t play well then they could be on their way to Mandalay.”

Ross McCrorie, the 20-year-old who was given the nod to start in defence for Rangers, was sent off five minutes into the second-half when he hauled down Celtic striker Moussa Dembele inside his own penalty box.

Dembele took the resultant spot kick himself and promptly netted a Panenka that put his team 3-0 ahead against their 10 man opponents and as good as clinched their place in the final against Motherwell on Saturday, May 19.

However, McKinnon, who played at centre half for the Ibrox club between 1960 and 1971, is adamant that Rangers could have survived the loss of McCrorie and fought their way back into game.

“For me, it is all down to the defence,” he said. “They should be taking the blame. The very fact Celtic were getting shooting practice shows that something is wrong at Rangers that has to be corrected quickly. I would perhaps have played with a sweeper.

“Scott Brown is getting to be an old man now, but he is the star man every time they play. It is scary. He is a good player to have in your team because he gets stuck right in. He kicks people and makes it look as though they are kicking him. He is very clever in these tackles.

“The centre halfs are certainly the crucial players in the defence. If one of them gets sent off then the other team has a huge advantage. The back line becomes dysfunctional. They all try to make up for it. But look what happened the last time Rangers played Celtic. Jozo Simunovic got sent off and they still got beat 3-2.”

The loss at Hampden on Sunday means that Rangers will not be able to end their seven year wait to lift a major trophy next month and McKinnon, who won every honour in the Scottish game during his own playing days, believes it underlines that major investment is needed before they can challenge their city rivals.

“I couldn’t believe it,” he said. “I thought they were ready now, were ready to compete with Celtic. Graeme Murty did well against Celtic in two games at Parkhead last year. The scores were at least acceptable. They were good results. I didn’t see it coming. I thought they were doing well under Murty.

“To suddenly collapse like that is a disaster for him and his future prospects. It is a shame because he is a nice man who has done well in difficult circumstances. But the guys in charge can’t stand for any scores like that. They will have to do something.

“But how do they do that if they don’t have the dollars? They can’t get the manager they want because he costs too much money. It is all to do with finance and they don’t have the spending power just now.

“It’s a hot potato. If there was money to buy a good centre half, a good central midfielder and a good forward who could put the ball in the net it would help. They need that. But they don’t have the finances.

“The Rangers fans are fantastic. Ibrox is packed for every game. There were a lot of them at Hampden on Sunday. The supporters are sticking by them. But how much can they take? They must be bewildered by results.”