ALEX MCLEISH is that rarest, perhaps even unique, of creatures in that he is a legend at both Aberdeen and Rangers.

So there is nobody in a better position to speak about Ryan Jack, for one more week the captain at Pittodrie, but is odds-on to be at Ibrox next season unless something truly left-field happens.

In case anyone doesn’t know, these two clubs are not pals. Indeed, such is the hostility that Jack is may become the Alfie Conn of his day and, to be fair, Alfie is still thought fondly of on both sides of the Glasgow divide.

Read more: Pedro Caixinha: I now know the style of football which can take Rangers back to the topGlasgow Times: Alex McLeish looks ahead to the Scottish Cup semi-final between Celtic and Rangers

Jack is a Rangers fan. Rangers want him. He is out of contract and has been an outstanding servant to his hometown club for 244 games. So what’s the problem? Erm, well, according to some just about everything.

“I think they should lay off,” said Big Eck about young Ryan. “He’s a professional, he has shown his strength as a captain. A lot of people like their own egos to be splashed across the papers but he’s a team player and a boy who will give everything for Aberdeen in this game.

“I’m sure the professionalism he has shown throughout his career at Aberdeen will shine through.

"I would play him in the cup final on Saturday, definitely. I don’t believe his mind will be straying elsewhere and I’m sure the majority of Aberdeen fans will get right behind him. You’ll get the occasional one who says he shouldn’t be going to Rangers and will hate him for the rest of their life because of it.

“But the modern day footballer has to do what he can for his career and they certainly have all the power nowadays because of the Bosman ruling.

“He’s also not won many trophies so he’ll be desperate to lift that cup. If he can leave Aberdeen on the high of lifting the Scottish Cup then it’s a memory that will live with him forever.

“When Charlie Nicholas was about to leave for Celtic he played in the (1990) cup final and I don’t recall any fans saying he shouldn’t play, or that he’d be booed. Charlie strolled up and took that penalty with the calibre of finish that you would expect of the class act that he was. Although I’m sure he tried to put it over the bar, so it must have been a miss-kick!”

Read more: Pedro Caixinha: I now know the style of football which can take Rangers back to the top

That certainly is a way for Jack to arrive at Rangers as hero; by scoring the winner against Celtic to stop them winning the treble, a feat last managed by McLeish at Rangers in 2003.

That was against Martin O’Neill’s Celtic, who made the UEFA Cup Final that season, so it was a million miles from a mean feat and, indeed, it’s a feat that can be overlooked.

“It’s got to be my best achievement,” says McLeish of that clean sweep. “Winning the Carling Cup with Birmingham against Arsenal was massive because it’s almost like this game on Saturday in that we weren’t given a prayer and Arsenal were supposed to be so far ahead of us but we outplayed them on the day, it was not just a lucky win.

“Helicopter Sunday was the biggest thrill of my career. When the Rangers fans erupted when Motherwell scored the equaliser and that was shivers down my spine like never before. But to get the treble with the style of play we had in that Rangers team at that time and the manner in which we did it was incredibly satisfying.”

Another reason for Rangers fans to love their old gaffer was the fact he put one over Celtic as a player so many times. Never mind that he was the last manager to win a treble, he was the last Aberdeen captain to lift the Scottish Cup.

That came in 1990, the first final that went to penalties, which in truth was the only memorable things about a dreadful incident-free game.

As mentioned above, Charlie Nicholas scored in the shoot-out, roughly a week before he returned to Celtic, but something perhaps forgotten is that cool spot-kick supplied by the big ginger centre-half.

“The memories are fantastic because that week the football writers had voted me the Player of the Year,” recalls McLeish. “So when it’s 4-4 after five penalties each Jocky Scott (the Aberdeen coach) says ‘who’s taking the next one?’

“When I said I will he asks ‘are you confident you’ll score?’ I said not really but as captain I think it’s my duty and I don’t see anybody else putting their hand up.

“So I walked up from the half way line and I think I went into a bit of a trance. The crowd looked like cardboard cut-outs and the noise seemed to be coming from speakers. It was surreal.

“So I thought to myself I’m just going to stick it where I always put my penalties - pass it hard into the goalie’s left and if it’s hit firmly and accurately enough it doesn’t matter if he goes the right way, he shouldn’t get it.

“But the devil on the other shoulder was saying ‘God’s sake, I’ve just been voted Player of the Year. This is where I get egg on my face.’

“Anyway, I had a good run up - none of that stupid little jinks and hesitation stuff - and passed it firmly into Packie Bonner’s top left hand corner. He went the right way - but no chance, Packie!”

Alex McLeish was speaking at a William Hill media event. William Hill is the proud sponsor of the Scottish Cup