Celtic took another step closer to the Ladbrokes Premiership title but they made hard work of overcoming St Mirren 2-0 at the Simple Digital Arena.
Striker Timothy Weah headed in the opener after 14 minutes before Buddies keeper Vaclav Hladky saved an Olivier Ntcham penalty.
The visitors had been wasteful and also allowed a much-changed side a few chances to draw level but substitute Ryan Christie sealed the win with a deflected shot with five minutes remaining to keep the Hoops 13 points clear of Rangers with just six fixtures remaining.
Neil Lennon's side host Livingston on Saturday in the last match before the split and it is surely now a matter of when, not if, the league is won.
Oran Kearney's St Mirren's side remain two points ahead of bottom side Dundee.
The visitors went into the game on the back of a morale-boosting 2-1 win over Old Firm rivals Rangers at Parkhead on Sunday and with the benefit of a healthy lead, Lennon made changes with Jozo Simunovic, Emilio Izaguirre, Oliver Burke and Weah back in the side.
St Mirren were similarly buoyed, having leapfrogged Dundee at the bottom of the table with a 2-1 home win over the Taysiders on Saturday.
Kearney, perhaps with a view to Hamilton on Saturday, changed more than half his side with Anton Ferdinand, Laurentiu Corbu, Cameron MacPherson, Jim Kellerman, Stephen McGinn and Cody Cooke returning.
In the 10th minute of a scrappy opening, Parkhead defender Kristoffer Ajer blasted over the bar from 12 yards after being set up by Callum McGregor.
It was not the first chance of the game, however, as moments earlier Buddies striker Duckens Nazon took a fresh air swipe at the ball just eight yards out.
But Celtic were soon ahead. A slick move involving McGregor, Mikael Lustig and James Forrest ended with the Sweden international drawing a save from Hladky with a drive.
When his second attempt spun into the air Weah, on loan from PSG, headed in off the crossbar and the ball sneaked just over the line.
Burke slashed a shot wide of the target and then, just before the half-hour mark, Buddies midfielder Kellerman inexplicably handled from Izaguirre's deflected cross.
However, Hladky parried Ntcham's unconvincing spot-kick with the French midfielder lofting the rebound over via the top of the bar.
Burke fired against Hladky from 12 yards early in the second half but Saints then twice came close.
In the 52nd minute Hoops keeper Scott Bain did well to tip Cooke's curling shot past the post after a mix-up in the Celtic defence with Haiti international Nazon missing a header at the back post from the subsequent corner.
Then, a quickly-taken free-kick from St Mirren defender Mihai Popescu in the middle of the park caught Celtic napping and found Nazon but when confronted by Bain he tried to turn on to his right foot, was smothered, and the chance was lost.
Christie, on for Ntcham after 64 minutes, looked lively as he rallied his team-mates and his goal eased the nerves albeit keeper Hladky was unsettled after a firecracker of some sort appeared to go off beside him.
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