Postpublished at 21:59 British Summer Time 3 April 2015
Join us again tomorrow for live coverage of another five crucial games in the Scottish Premiership.
Forrest and Johansen score for Celtic
Top beat bottom in Scottish Premiership
Celtic eight points clear at top
St Mirren four points adrift at foot
Clive Lindsay
Join us again tomorrow for live coverage of another five crucial games in the Scottish Premiership.
Thanks for your company tonight when Celtic took another giant stride towards retaining the Scottish Premiership title and a domestic treble. St Mirren, meanwhile, were pushed closer to the abyss of relegation.
"They were defending very deep and very brave. it was difficult to break them down.
"We were patient but were not clinical enough, but it was a fantastic first goal.
"After that, we controlled the game and I don't think they had a goal chance.
"James Forrest had a hard time against the full-back, but were were not going to take him off.
"We have been patient with him and we are getting the reward for it."
"The boys were excellent and showed the heart and desire I asked from them.
"I was just disappointed with the goals. It was a lapse in concentration for the first and I don't think it was a penalty for the second.
"I thought we might have held on, but once you lose the first goal against a quality side like Celtic, it is always going to be difficult.
"Now we need to take every game as it comes and win every single one of them."
"St Mirren defended well and made it tough for Celtic. In the second half, Celtic were looking frustrated until James Forrest popped up just before it looked like he was coming off. But St Mirren didn't really create anything tonight."
St Mirren have still only won once at home this season and, with seven games left, remain four points adrift of Motherwell at the bottom of the table. That position could become worse tomorrow should Well pick up anything away to Kilmarnock.
Without being terribly impressive - perhaps not needing to be - Celtic take the three points to stretch their lead over Aberdeen at the top of the Scottish Premiership to eight points.
It almost gets worse for St Mirren as Celtic substitute Gary Mackay-Steven flashes a superb drive on the turn just wide.
Stuart Gillespie: "Any chance Pat Bonner can say one of our players is about to be subbed so he can score?"
St Mirren manager Gary Teale had played his last cards seconds before the second goal, with veteran striker Stevie Thompson and Emmanuel Sonupe coming on for Stevie Mallan and James Dayton. It looks like the change came too late and there is no way back now for the home side.
Celtic win a penalty when James Forrest's shot strikes the hand of Viktor Genev in front of goal and Stefan Johansen scores from the spot.
Gary Mackay-Steven comes into the Celtic midfield in place of Kris Commons, while 18-year-old Lewis Morgan replaces Kieran Sadlier in the home midfield.
"You almost feel sorry for St Mirren. They have had the best performers on the night and they have nothing to show for it."
Instead of being substituted, James Forrest switches to the other side of the park as Adam Matthews goes off to be replaced with Efe Ambrose at right back and Nir Bitton comes on for Stuart Armstrong.
It looked like James Forrest was about to be hooked by Celtic manager Ronny Deila, but instead the winger side-foots the opening goal from Adam Matthews' low cross after a fine Scott Brown through ball.
"Jeroen Tesselaar has James Forrest in his pocket and I'm surprised Ronny Deila has not taken the winger off."