Scottish Cup round-up: Albion Rovers face Celtic after dramatic win
Celtic will travel to Coatbridge in the Scottish Cup after Calum Ferguson's stoppage-time winner for Albion Rovers against Queen of the South.
Rovers were reduced to 10 men before prevailing 2-1 in the third-round tie.
Lawrence Shankland scored twice as St Mirren thrashed Lowland League outfit Spartans 5-1, while East Fife drew 1-1 at home to Edinburgh City.
Ayr United won 1-0 away to Brechin City and will next host Queen's Park after the Spiders beat Montrose 2-0.
In Coatbridge, Rovers took the lead after only 16 minutes through Mick Dunlop's header, but Jamie Hamill equalised for their Championship visitors with 14 minutes remaining.
The League One part-timers' cause appeared likely to be hampered when Ryan Wallace was shown a second yellow card with three minutes left.
However, Calum Ferguson finished the game from close range in the final seconds after a quick break to inflict a sixth defeat in seven games on a Queens side still seeking a new manager.
Two goals within five minutes in the first quarter of the match sent St Mirren, sitting bottom of the Championship, on their way to a fourth-round meeting with Dundee at Dens Park.
Shankland and Stevie Mallan fired in those early goals and Kyle McAllister added a third before the break - driving his first senior goal in off the crossbar.
A John Sutton header and a cool finish from Shankland extended the home side's advantage in Paisley before Jack Beesley turned in a late consolation for Spartans.
At Glebe Park, Andy O'Connell had the winning touch for Ayr in a tight game, providing the finish from Gary Harkins' pass in the 70th minute.
Having ended a run of five games without a win, the Championship side will now face another League One outfit, this time at home, after Queen's Park overcame Montrose at Hampden.
David Galt's low volley gave the Spiders a 15th-minute lead then Paul Woods ran half-way up the park to fire past goalkeeper Allan Fleming nine minutes after the break to send the League Two strugglers to another defeat under caretaker manager John Holt.
Livingston must wait to learn who will be travelling to West Lothian in the fourth round after Edinburgh extended their unbeaten run to seven games with a draw in Methil.
City, who remain bottom of League Two despite their fine form, made the breakthrough after 40 minutes through Ouzy See's low drive.
However, the League One Fifers, who have now gone eight games without a win, hit back 19 minutes into the second half thanks to Jason Kerr's header - the substitute's first kick of the ball - to secure a replay.