To most inside Hampden Park, apart from referee Steven McLean and his additional assistant Muir, stationed behind the goal, it looked clear that Caley Thistle defender Josh Meekings had used an arm to prevent a Leigh Griffiths header going into the net, just a yard out.
A scored penalty seconds before the break would have added to Virgil van Dijk’s opener for the Parkhead men and with the Highlanders probably reduced to 10 men, the Hoops manager claimed the game would have “finished” with his side looking forward to the final against Falkirk on May 30.
But the match then further turned against the Scottish League Cup winners early in the second-half when keeper Craig Gordon was sent off for tripping Inverness striker Marley Watkins to concede a penalty, which Greg Tansey scored past replacement keeper Lukasz Zaluska.
Inverness striker Edward Ofere’s low drive in the 96th minute was cancelled out by Celtic substitute John Guidetti’s free-kick but with four minutes remaining full-back David Raven grabbed the winner for the Highlanders.
Afterwards the Celtic boss reacted to questions about the game’s biggest incident.
He said: “I don’t think I have to say much about that. I think everybody saw what happened. Maybe we need seven referees? One on each post.
“Their one task is to look at what is happening in the six-yard box and on the goal line. You can’t blame the main referee for that. Referees make mistakes as well but this mistake was very hard to take. It’s a hard blow for the boys and for us. We’re very disappointed and we had control 11 versus 11 and we should have killed the game off.”
Deila had no complaints about Gordon’s dismissal as he added: “That was okay. The rule is as it is. I think the rule is very hard, but that’s nothing to do with the ref.”
An emotional Raven reflected on a “dream come true” after his winner sent Inverness through to their first-ever Scottish Cup final.
The 30-year-old, who has only managed a handful of goals in his entire career, struggled to describe how he felt following an eventful match which he admitted could have gone either way.
He told Sky Sports: “I don’t know really, a bit emotional to be honest, got tears in my eyes. I thought it was just our day and to score the winning goal today is a dream come true. In a cup semi-final against Celtic, I can’t believe it.
“It was topsy-turvy and it could have gone either way.”
Inverness boss John Hughes said: “The sending off changed the game in Inverness’ favour, but as I said before the game, what these boys have done for me since I came to the club, they deserve that today.
“I’m absolutely delighted to be there. Well done to the boys and supporters.”
On their final opponents, Hughes said: “A small club, Falkirk have had some wonderful times there and it’ll be a right good cup final, and hopefully it is for Scottish football.”
Esson, Raven, Warren, Meekings, Shinnie, Draper, Tansey, Watkins, Christie, William (Ross 74), Ofere
Gordon, Matthews, van Dijk, Denayer, Izaguirre, Brown, Bitton, Forrest (Zaluska 56), Johansen, Commons (Tonev 90), Griffiths (Guidetti 98)