The breakthrough - and it has been coming.

Will Ferry whips a corner towards the front post and Ross Graham beats goalkeeper Ellery Balcombe to the ball, the centre-half glancing a powerful header into the net.

That comes after a good five minute spell in which United had St Mirren penned back in their box and Balcombe was looking uncomfortable with cross balls. Making that dominance pay.

Martin Dowden
BBC Sport Scotland at Tannadice

These two sides are fairly evenly matched on this evidence, with both lacking, so far, that little bit of quality where it counts.

United midfielder Craig Sibbald has come closest with his excellent effort off the bar.

It might be a case of first goal the winner the way this is heading.

Derek McInnes is going to have one sore voice tomorrow morning.

He screeches to Bruce Anderson, "good work", in agonising fashion.

Better from the visiting frontline, certainly in the eyes of the Kilmarnock manager.

United hit the bar again - in bizarre circumstances.

It's a long throw from the left that no-one connects with and goalkeeper Ellery Balcombe just watches as the ball bounces up on to his crossbar.

You can't score from a throw-in, so St Mirren might have gotten lucky if it had gone in.

How many times have we seen Stephen O'Donnell roll the ball with his right and fling an enticing ball into the box?

Countless, for both Motherwell and Kilmarnock.

Another splendid one here, but big striker Zach Robinson loitering at the back-post can't connect.

Andy Burke
BBC Sport Scotland at Fir Park

Not much to get excited about in the opening quarter of this cup tie.

Both sides are trying to knock it around, looking to create an opening, but both are so far lacking any sort of cutting edge in the final third.

Marley Watkins had a decent sight of goal on the counter for Killie, but other than that we've been starved of any meaningful goalmouth action.

Scott Allan
Former Celtic & Hibernian midfielder on BBC Sportsound

I think Hibs will play Martin Boyle up front along with Kukharevych. They got the runaround last week and couldn't get out their own half against Celtic.

Kilmarnock forward Bruce Anderson is down holding his back after a clattering landing.

Not appreciated round the stands, though. The boos ring loud.

That's a yellow card for Declan Gallagher as the United centre-half completely wipes out striker Toyosi Olusanya on the turn.

It's a high tackle in the final line of defence. Maybe a lucky boy.

Killie are growing into it, with Marley Watkins letting fly from just inside the box.

It's off target, but the visitors are getting into better positions.

Despite that chance from Craig Sibbald, St Mirren have been the better team.

Fraser Taylor turns nicely on the right and whips in a deep cross that finds Mikael Mandron, but the striker's header is tipped over the bar by goalkeeper Jack Walton.

What an effort from Craig Sibbald!

Ellery Balcombe was impressive against Brann, but the St Mirren goalkeeper flaps at a cross and the ball is only cleared to the United midfielder 25 yards from goal and he rattles the crossbar from distance.

Probably not the player you'd want a ball just outside the six-yard box to fall to.

Stephen O'Donnell - who knows what he's doing up there - lingers in the box and latches on to a ball from the left.

It's stuck under the right-back's feet, though, and Killie can clear.

Bright start for Motherwell, dominating the ball and trying to work it out to the right.

Lennon Miller wins a free-kick pretty central, about 30-yards from goal, but the hosts can't do anything with it.

Killie yet to get a feel of the ball.

St Mirren go close after just two minutes!

A long throw is controlled in the box and flicked to Alex Iacovitti, the centre-half slashes at goal and goalkeeper Jack Walton tips it behind. Not far away at all.

We're up and running at Fir Park and Tannadice.

Andy Burke
BBC Sport Scotland at Fir Park

Every time I am here, I am struck by the quality of the Fir Park pitch. It really is magnificent and the quality every club should be aspiring to.

The sun is shining and we are all set for a very intriguing cup tie.

Martin Dowden
BBC Sport Scotland at Tannadice

United will rightly prioritise preserving their top-flight status, but a strong cup showing at this early stage might work wonders in aiding that. Cup quarter-finals are not to be sniffed at.

They seem to have recruited well and Luca Stephenson, on loan from Liverpool, starts this afternoon, offering more promise and potential within their squad.

St Mirren seek consistency of performance given they can't quite achieve consistency of selection right now. That will come soon presumably now that their European adventure is at an end.

A first competitive start for young Fraser Taylor will give an insight into what unseen pearls might lie within Stephen Robinson's squad as they look to match the heights of last term.

This has the makings of quality cup tie.

Celtic: Schmeichel, Johnston, Carter-Vickers, Scales, Taylor, McGregor, O'Riley, Hatate, Kuhn, Forrest, Maeda.

Substitutes: Sinisalo, Palma, Idah, Yang, Holm, Bernardo, Ralston, Welsh, Turley.

Hibernian: Bursik, Miller, Bushiri, Ekpiteta, O'Hora, Obita, Newell, Moriah-Welsh, Campbell, Boyle, Kuharevich.

Substitutes: Smith, Levitt, C Cadden, Amos, McKirdy, N Cadden, Bowie, Megwa, Molotnikov.