Celtic and St Mirren serve up mad Scottish Cup semi-final: calamity, 17y/o debutant and fairytale final

This was a wild occasion at Hampden, a game that will live long in the memory. The outcome is that Celtic are in next month's final against Dunfermline Athletic after prevailing 6-2 following 120 pulsating minutes. If the first semi-final a day previously between the Pars and Falkirk was low on entertainment, this certainly made up for it.

Celtic displayed why they have struggled this season - but why the remain in the hunt for silverware. Pre-match, manager Martin O'Neill urged his players to keep their double hopes alive. They answered his call - but did little for the 74-year-old's heartrate in the process.

The drama started early. The clock had just struck a minute when St Mirren defender Miguel Freckleton passed the ball back to goalkeeper Ryan Mullen. The stopper took a moment to look up and pick his pass. He had not bargained for the most energetic, rapid man on the pitch chasing him down.

Mullen's pondering was painful and perilous. By the time he saw Daizen Maeda coming, it was too late. His clearance was blocked by the striker and the ball slithered over the goalline despite the keeper's vain attempts to stop it.

It set the tone for a barnstorming match, a Hampden classic, where an edgy Celtic exacted a modicum of revenge for losing the Premier Sports Cup final here back in December, when they left with their tail between their legs.

Mullen was on the bench that day. He is the No 2 keeper at St Mirren but Shamal George picked up a training ground knock during the week and wasn't fit enough to play. Mullen had come on for him the week before at Celtic Park for another issue and had fared fine. There was no suggestion of what was to come.

Mullen understandably looked jittery with the ball at his feet after the Maeda incident and on 14 minutes, just after a close shave when being harried by Maeda once more, he crumpled the turf disconsolately. He was unable to continue with his own injury.

The 17-year-old keeper makes his debut

So it was over to Grant Tamosevicius, a 17-year-old who had never played a senior match. The Scottish teenager of Lithuanian descent had warmed the bench three times previously for St Mirren and spent a month on loan at Arbroath in November. The kid was not qualified to play in a match of such magnitude.

Nevertheless, St Mirren interim coach Craig McLeish had no choice. Tamosevicius was summoned and for a player of such tenderness, he coped well with the moment.

He clutched an effort from Benjamin Nygren and then beat away a fierce Maeda drive. St Mirren grew into the game, Celtic could not control the midfield and their own keeper, Viljami Sinisalo, made an excellent save from a Liam Donnelly header before his own moment of near-calamity.

The Finn dithered on a back-pass and smashed it off Killian Phillips. The ball bounced over him but not with enough pace to completely outwit the stopper. He did well to claw it off his own line but the episode heightened the tension in the Celtic support. They were not in control.

So when Anthony Ralston leathered the ball home in the third minute of first-half stoppage-time, via the underside of the bar after good work from Sebastian Tounekti, it gave them breathing space. They required it.

St Mirren threw caution to the wind after the interval. The arrears were halved on 53 minutes when Mikael Mandron headed a Declan John cross back across goal and into the net. Hope coarsed through the Paisley faithful.

The game was now even. Both teams pressed for the next goal but neither showed enough composure in a 20-minute spell thereafter despite some half-chances in the penalty box.

Celtic replenished their midfield with the introduction of Alex Oxlade-Chamberlain and Luke McCowan for Arne Engels and captain Callum McGregor. It is rare to see the skipper withdrawn at such a pivotal point in the match but fitness issues continue to linger. He did not have a vice-like grip on the game in any case.

St Mirren finished the game the stronger of the two. They brought on Conor McMenamin for Liam Donnelly to add an extra attacking player on the pitch. Nothing to lose now.

Celtic were clinging on. Ball retention was non-existent. Sinisalo saved from McMenamin with his foot and then palmed away the rebound from Mandron. Their sizeable support showed their displeasure. Tamosevicius was now a spectator with them.

Four minutes of stoppage time flashed up. St Mirren weren't done yet. Jake Young flicked on a Freckleton pass and Mandron was through on goal. No mistake this time. He belted the ball into the bottom corner and extra time was upon us.

It would have been easy for Celtic to fold. Pack up and go home. This has been a trying season, what's another sob story to add to it. But they regrouped, and showed why they are still in the fight for the Premiership and now in the Scottish Cup final.

Substitute Kelechi Iheanacho glanced home a cross from James Forrest on 96 minutes, with Tamosevicius in no-man's land. It was 4-2 moments later when the ball broke into the path of McCowan, who steered home. By 100 minutes it was 5-2, Iheanacho clipping home with a deft finish. Then Nygren slotted in after a cutback from Maeda on 102 minutes. Job done. Job well and truly done. In the space of six minutes.

Where was this Celtic version beforehand? O'Neill will have his last dance on May 23, back at Hampden against Dunfermline, who are managed by his former captain Neil Lennon. It surely can't be as dramatic as this ...