Holders St Johnstone crashed out of the Scottish Cup against Kelty Hearts as their nightmare run continued.
Kallum Higginbotham scored the only goal in extra-time as the cinch League Two leaders claimed a major scalp in their first season as a league team.
Last season's double cup success is a distant memory for Callum Davidson and his team with defeat in Fife making it 10 consecutive losses.
There were no other shocks in the afternoon matches as Motherwell narrowly averted an upset against Morton.
Robbie Muirhead put the Championship side ahead at the end of the first period of extra-time at Fir Park but Kevin van Veen equalised from the spot and Liam Donnelly sealed a 2-1 victory from long range in the 120th minute.
Celtic booked their place in the fifth round with a 2-1 win over Alloa Athletic which ended with a hint of nerves for the Parkhead side.
First-half goals from Greek striker Giorgos Giakoumakis and winger Liel Abada had the Hoops comfortably ahead by the interval against cinch League One side at the Indodrill Stadium.
That former Rangers captain Barry Ferguson was the host side’s manager added spice to the tie which became interesting when Alloa striker Conor Sammon reduced the deficit with a header.
However, Celtic denied their hosts any clear-cut opportunities to draw level although the victory came at some cost for Ange Postecoglou as skipper Callum McGregor, Abada and Yosuke Ideguchi had to go off with various injuries.
Dundee United needed extra-time as Dylan Levitt’s classy goal earned a 2-1 win at Kilmarnock. Marc McNulty gave the visitors an early lead but Killie soon hit back through Rory McKenzie and the Championship side had the best of the chances before Levitt finished in style.
The five non-league teams in the last 32 were all beaten but there were some close calls.
East Kilbride came closest to progressing, losing 5-3 on penalties at Peterhead after the tournament’s top goalscorer, Joao Pereira Victoria, hit a double for the Lowland League side in a 2-2 draw.
Clydebank were also agonisingly close to causing a shock before going down 4-3 to Annan at Holm Park. The Bankies went ahead for the first time in the tie early in extra-time when Ciaran Mulcahy scrambled home, but Rob McCartney levelled in the 119th minute and Iain Anderson won it for the visitors in the third minute of time added on.
Hearts had earlier seen off the challenge of Auchinleck Talbot with Liam Boyce netting a double in a 5-0 win in Ayrshire, while Darvel were beaten 3-0 at Arbroath courtesy of on-loan Livingston striker Jack Hamilton’s hat-trick.
Banks O’Dee put up a good fight against Raith but Sam Stanton broke the deadlock midway through the second half and late goals from substitutes Matej Poplatnik and Aiden Connolly sealed a 3-0 win.
Ayo Obileye’s first-half penalty was enough to send Livingston past Ross County’s expense in the only all-Premiership clash of the round.
Leigh Griffiths struck a 62nd-minute penalty as Dundee won 1-0 at Dumbarton while Aberdeen saw off Edinburgh City 3-0 thanks to goals from Ryan Hedges, Christian Ramirez and Lewis Ferguson.
St Mirren booked their place in the last 16 with a comfortable 2-0 win away to Ayr United thanks to first-half goals from Kyle McAllister and Greg Kiltie.
Partick Thistle ended Airdrie’s five-match winning run with a close-range finish from Brian Graham in the 25th minute enough to see the Jags through at Firhill despite the hosts losing Tunji Akinola to a red card just after the break.
