Ali Crawford is sent clear by a fine Craig Bryson through ball.

The midfielder has a two versus one situation, but instead of finding team-mate Michael O'Halloran, he tries an overambitious chip from all of 30 yards, but it is wastefully wide.

Nick McPheat
BBC Sport Scotland at Hampden

The Celtic end have unveiled a massive banner of Bertie Auld's face on the 67th minute.

There's plenty of pyrotechnics going off in the west stand as Scotland winger James Forrest prepares to come on.

Allan Preston
Ex-St Johnstone defender on BBC Sportsound

Ouch!published at 66mins

66mins

Celtic 0-0 St Johnstone

Jota earns another earful from James Brown as the winger tries to win a penalty for a second time.

Then Celtic centre-half Cameron Carter-Vickers and Jamie McCart are left in agony as the Saints defender clears in front of his own goal as Kyogo Furuhashi heads into the six yard box.

Image source, PA Media

Saints midfielder Murray Davidson is next into the referee's book for failing to retreat as Celtic looked to take a quick free-kick.

It's very much in the balance at Hampden.

Who's going to win this increasingly tense semi-final? Thumbs up for favourites Celtic, thumbs down for holders Saints....

Pat Bonner
Former Celtic goalkeeper on BBC Sportsound

Centre-half Cameron Carter-Vickers fires a header straight at Zander Clark from a corner and then the Saints goalkeeper gathers at the front post from Kyogo Furuhashi's dangerous cross as Celtic continue to press.

A trio of bookings as Jamie McCart trips Kyogo Furhashi as the winger looks to break clear.

The centre-half is yellow carded for the foul while Kyogo and Saints midfielder Craig Bryson follow for a bit of afters.

The second half has started the same as the first, with Celtic with almost all the possession.

However, as yet, Saints have handled it much better this time round and are holding steady.

There's a lot of concern for David Wotherspoon, but the midfielder manages to walk off.

Just when you think he might be able to continue, on-loan Bolton Wanderers man Ali Crawford is sent on as a replacement.

Ouch!published at 48mins

48mins

Celtic 0-0 St Johnstone

St Johnstone's David Wotherspoon goes down holding his knee after a clash with Anthony Ralston.

A stretcher is coming out for the influential midfielder.

Celtic get the second half under way.

Are we heading for extra time in the first League Cup semi-final of the weekend?

Here come the teams for the second half...

Allan Preston
Ex-St Johnstone defender on BBC Sportsound

For all of Celtic's dominance of possession, they have yet to force Scotland squad goalkeeper Zander Clark into a save.

Crucial blocks from Craig Bryson and Jamie McCarth exemplified the determination of the League Cup holders to retain the trophy and cause another shock.

Image source, SNS

Celtic threatened to sweep aside St Johnstone as they swept forward with menace in the opening minutes, inspired the wing trickery of Jota.

But the holders survived the early pressure and it remains all square at the break.

We're still no wiser about who will reach this season's League Cup final.

Image source, SNS

Allan Preston
Ex-St Johnstone defender on BBC Sportsound

Image source, SNS

So close to a goal out of the blue from St Johnstone.

Chris Kane gathers a pass from David Wotherspoon and the striker's shot on the turn from 25 yards whizzes past goalkeeper Joe Hart but also wide of the far post.