Match ends, Celtic 4, St. Mirren 1.
Celtic survived an early scare against Championship side St Mirren to reach the Scottish Cup semi-finals.
The visitors took a shock lead on 13 minutes when John Sutton nodded down for Harry Davis to tap home.
Two Celtic goals in as many second-half minutes from Mikael Lustig and Scott Sinclair turned the match on its head and the home side never looked back.
Moussa Dembele and substitute Leigh Griffiths struck as the 36-times winners reached the last four.
Celtic paid Saints the respect of naming an unchanged side. Yet even though the Paisley club had won their previous two league matches, they were still being offered at odds of 40-1 for a victory here.
Emotion was thick in the air, as the match was preceded by a minute's silence in honour of Lisbon Lion Tommy Gemmell, who died this week.
Incredibly, it was St Mirren who took the lead. It was a cleverly worked free-kick down the left, as Stevie Mallan set up Cammy Smith with a disguised pass to the byline. His cross was nodded back into the heart of the six-yard box by Sutton and Davis was there to turn the ball home.
As the match progressed, it became clear Saints were equipped to give Brendan Rodgers' side as big a domestic test as they have faced this season at Parkhead.
In the wake of the goal, they sat in with a very disciplined 5-3-2 formation and survived some close calls, the most significant of which was a Scott Brown cut-back that Dembele made a total hash of.
Rodgers replaced the ineffective Gary Mackay-Steven with Patrick Roberts at half-time - but seven minutes into the second period, Celtic had a remarkable escape.
Mallan drove in a low free-kick to the near post which Dembele managed to divert against his own crossbar. It proved to be the turning point of the match.
With 58 minutes on the clock, Celtic were level. Roberts' delivery into the box from a free-kick out wide was good and Lustig headed home to give his team a grip on the tie again.
Not much more than a minute later, they were ahead with a quite audacious goal from Sinclair. The Saints defence looked to have the situation under control but somehow the striker opened his foot and curled an outrageous effort into the top corner.
It was over as a contest now. Celtic made it 3-1 with an electric break with Sinclair at its heart. He powered forward, released Roberts, took the return and laid it on a plate for Dembele to tap home.
Saints were suffering in a way they didn't deserve. Griffiths, who had a huge influence on the game after coming off the bench, added a fourth with a fine left foot shot from just inside the box and the Paisley side were out on the floor.
Celtic march on to the semi-finals. St Mirren's thoughts turn back to Championship survival.
- 6BittonBooked at 52minsSubstituted forGriffithsat 54'minutes
- 16Mackay-StevenSubstituted forRobertsat 45'minutes
- 14S ArmstrongSubstituted forKouassiat 77'minutes
- 24de Vries
- 2DemetriouBooked at 58mins
- 6MackenzieSubstituted forBairdat 75'minutes
- 42MagennisSubstituted forStorieat 83'minutes
- 9SuttonSubstituted forLoyat 70'minutes
- Steven McLean
- Shots on Target
Second Half ends, Celtic 4, St. Mirren 1.
Foul by Leigh Griffiths (Celtic).
Gary Irvine (St. Mirren) wins a free kick in the attacking half.
Foul by Dedryck Boyata (Celtic).
Cameron Smith (St. Mirren) wins a free kick on the right wing.
Foul by Dedryck Boyata (Celtic).
Jack Baird (St. Mirren) wins a free kick in the attacking half.
Corner, Celtic. Conceded by Gary Irvine.
Substitution, St. Mirren. Craig Storie replaces Kyle Magennis.
Attempt saved. Cameron Smith (St. Mirren) right footed shot from the left side of the box is saved in the top centre of the goal.
Goal! Celtic 4, St. Mirren 1. Leigh Griffiths (Celtic) left footed shot from outside the box to the bottom right corner. Assisted by Patrick Roberts.
Substitution, Celtic. Eboue Kouassi replaces Stuart Armstrong.
Corner, Celtic. Conceded by Jack Baird.
Substitution, St. Mirren. Jack Baird replaces Gary Mackenzie.
Attempt missed. Moussa Dembele (Celtic) right footed shot from the centre of the box is close, but misses to the left.
Attempt missed. Lewis Morgan (St. Mirren) right footed shot from the left side of the box is close, but misses to the right.
Substitution, St. Mirren. Rory Loy replaces John Sutton.
Foul by Patrick Roberts (Celtic).
Stelios Demetriou (St. Mirren) wins a free kick in the attacking half.