See in-play clips of best goals
Muirhead (pen) gives Livingston lead; White levels for County; Montano restores lead; Hale equalises again to force extra time; Shinnie forces in winner towards end of extra time
Morris nets for Aberdeen at Elgin; Duk adds second & third goals
Olusanya double for St Mirren; Queen of the South pull one back
Hibernian 2-0 Clydebank
Brian McLauchlin
BBC Scotland at Easter Road
The second goal for Hibernian came right in front of the 2,500 travelling Clydebank fans and you could see some of them slump back into their seats.
Hibs have flown out the traps in the second half and look in the hunt for more goals.
Image source, SNS
Jordan White
A long County free-kick is aimed for the back post. It's nodded back into the mixer and White bundles in from close range.
Game on!
Watch: County level against Livingston
St Johnstone 1-0 Motherwell
Kheredine Idessane
BBC Scotland at McDiarmid Park
He recently served a one-match ban and the Motherwell manager Stuart Kettlewell is in a wee bit of bother again, yellow-carded by referee John Beaton for his touchline remonstrations.
Not his day so far. He's losing and his side has been poor.
Elgin City 0-1 Aberdeen
So close to a second for Shayden Morris.
The Aberdeen winger's side-footed effort crashes off the outside of Elgin's front post.
Jamie Todd
Oh, we might just get an upset after all!
Watch: Todd brings Musselburgh level
Lewis McCann
Watch: McCann extends Dunfermline's lead
Elgin City 0-1 Aberdeen
Aberdeen start the second half on the front foot and Peter Ambrose fires low across the face of goal and wide after the striker races through on a long ball.
Rudi Molotnikov
Rudi Molotnikov finally gets his goal.
Martin Boyle picks out the 18-year-old at the back post and he makes no mistake in slamming home Hibs' second.
Watch: Molotnikov doubles Hibs' lead
Ross County 0-1 Livingston
Watch: Livingston score penalty against Ross County
Up and running again at most of the grounds...
HT: St Johnstone 1-0 Motherwell
Kheredine Idessane
BBC Scotland at McDiarmid Park
A large round of boos from the big Motherwell support tells you all you need to know about how that first 45 panned out. St Johnstone were miles better than their visitors and should be at least a couple of goals ahead. But for better finishing from Victor Griffith and Graham Carey, and better decision-making from goalscorer Makenzie Kirk, they would be.
Motherwell have been poor. Very poor. It's highly likely they'll be getting the mother of all roastings from manager Stuart Kettlewell in the dressing-room.
His counterpart Simo Valakari will be quietly satisfied with his first Scottish Cup tie as a manager so far.
Image source, SNSSimo Valakari is ahead against his former team
HT: Hibernian 1-0 Clydebank
After going a goal down after just 90 seconds and at times looking vulnerable at the back, Clydebank remain firmly in this game. Hibernian will be looking to up the pace in the second half and kill off any chance of a comeback from the West of Scotland side.
Image source, SNSHT: Cove Rangers 1-0 Forfar Athletic
Tyrone Smith
BBC Scotland at the Balmoral Stadium
Not a classic this one, but Cove won't care about that.
It was a nice goal too, Mitch Megginson played a lovely ball through to Adam Emslie who produced a really cool finish.
Cove have had the better of things, but they had a scare when Bradley Rodden's angled shot hit the bar.
HT: Dunfermline 2-0 Stenhousemuir
Jane Lewis
BBC Sport Scotland at East End Park
The home side have pretty much controlled this tie. Stenhousemuir have shown in patches what they could be capable of but Dunfermline have looked comfortable, passing the ball around well and getting forward with some intent.
Livingston leading in Dingwall is the only sniff of an upset and it would be a minor one, given the teams were league rivals last season.
Robbie Muirhead's penalty splits the sides, after Akil Wright's moment of madness. That's one to catch on the telly later.
It's been a stodgy one in Dingwall so far. James Brown hit the bar with a cross, while Stevie May tested Jordan Amissah with a powerful drive at the other end.
That's been about the best of it, apart from the penalty.
Queen of the South 0-2 St Mirren
Toyosi Olusanya's first-half double has St Mirren cruising towards the fifth round of the Scottish Cup.
Teenage wing-back Callum Penman - making his first start for the Paisley club - was heavily involved in both goals, hurling in a long throw for the opener, before landing a wonderful cross on Olusanya's head for the second.
Image source, SNSShayden Morris' goal gives the Dons a lead they just about deserve.
Fourth-tier hosts Elgin squandered a couple of early chances, but since the goal, the Premiership visitors could have extended their lead.
Image source, SNSA goal from Shayden Morris (right) separates the sides
Martin Boyle's early opener has Hibs leading their sixth-tier opposition at the interval.
Rudi Molotnikov has fired off-target on multiple occasions for the home side, while it took 44 minutes for Clydebank to muster up their first shot.
Image source, SNSSt Johnstone, who haven't won a game since November, lead at the break at McDiarmid Park.
A positive half for Simo Valakari's side who for a while now haven't had much to cheer about.
Wouldn't like to be in Stuart Kettlewell's dressing room at half-time...
Image source, SNSMakenzie Kirk's first half goal gives St Johnstone the advantage at the break
