Ken Owens is replaced by Shaun Evans up front.

Evans' first job is to throw in at this vital line-out.

Simon Berghan and Lewis Bean come on for Glasgow.

Some shuffling in the away backline, too. Sebastian Cancelliere is off, George Horne has gone to the wing, and Ali Price is on at scrum-half.

Peter Wright
Former Scotland prop on BBC Radio Scotland

Cancelliere being announced in the team would have given Glasgow a massive, massive lift.

For the tiniest guy in the world he is an amazing player and showed his class there.

Glasgow's respite is only temporary.

Another offside penalty. Another Costelow kick to the corner.

Another close-range raid pending.

Insane Glasgow defence. Insane.

Kieran Hardy is steaming for the line off the scrum, it looks like a try every day of the week, but Matt Fagerson wraps up the number nine and holds him short.

Scarlets rip it wide to the left, but again, Ryan Conbeer is seized upon by Ollie Smith and hauled into touch right by the corner flag.

That's mega.

We're approaching must-score territory here... Scarlets go for the scrum.

Scarlets go again from the scrum, with a penalty advantage, and an obstruction from Johnny McNicholl means that advantage is activated.

Ten minutes left.

Scarlets need two scores to reach the final.

"He touched the ball two times, it's just a knock-on," says Mathieu Raynal.

It's all about whether Ollie Smith makes a genuine attempt to catch the ball.

Raynal is happy he does.

It's an enormous call and it has incensed the home crowd.

Often, we see a player going for a pass with one hand and being dispatched to the bin. But one hand does not, in law, mean it's illegal.

Gareth Delve
Former Wales international on BBC Radio Wales

He has made a second attempt, he initially didn't have a chance of taking it, but when you go with one hand and don't take it you're in the bin.

Woah, woah, woah...

Could this be a penalty try?

Ollie Smith shoots up to intercept Johnny McNicholl's pass. If he misses it, Steff Evans has a run-in unchallenged.

He juggles it one-handed, and can't cling on.

Mathieu Raynal says knock-on only, but we're going to take a closer look...

Image source, Reuters

Oops, that's not so impressive from George Horne.

The scrum-half has his pocket picked off the line-out by Sam Lousi.

Scrum Scarlets, five metres out.

What a glorious attacking position.

Gareth Delve
Former Wales international on BBC Radio Wales

Owens was working hard to get back in field but it's very good cover from George Horne.

Superb defence!

A neat Scarlets move at the front of the line-out sends Ken Owens crashing towards the corner flag.

The hooker is fed by Sam Lousi, and has tiny George Horne in his sights.

It is an immense physical mismatch, but David halts Goliath's progress long enough for Sebastian Cancelliere to help bundle Owens out of play.

Scarlets are far from done yet.

A quickly taken free-kick gets them motoring into the Glasgow half, with Steff Evans doing the bulk of the damage.

Warriors leak one penalty advantage, then another, as Iestyn Rees hauls his team forth.

Sam Costelow punts to the corner.

Massive, massive moments, these.

Fourteen minutes to play.

Peter Wright
Former Scotland prop on BBC Radio Scotland

When you're 10ft 5in, it's easy to get yourself over a maul. JP du Preez is a really big man but he's got massive arms as well.

Colin Gregor
Former Glasgow Warriors back on BBC Radio Scotland

Mr Tickle's in there and grabs the ball.

Scarlets get a glimmer, but it's swiftly extinguished.

They win a penalty near halfway and boot to touch on the Glasgow 22.

But the immense frame of JP du Preez, whose arms are longer than most fully-grown anacondas, cocoons the ball and wins the Warriors a scrum.

Another Glasgow scrum penalty - won again by Zander Fagerson - eases the pressure.

Colin Gregor
Former Glasgow Warriors back on BBC Radio Scotland

Scarlets' line-out has creaked a bit because JP du Preez is a big lump and putting pressure on the Scarlets near their own line. Good patience from the Warriors forwards to just eke out the score.

Chris Paterson
Former Scotland international on BT Sport

Sometimes you can play wide too early. Scarlets defence almost gave them a little space to tempt them to go wide. The set-piece gets you go-forward as well, it's not only the big carries.

Colin Gregor
Former Glasgow Warriors back on BBC Radio Scotland

Everything that Glasgow do now is coming from the line-out they didn't have that in the first half, now they've got that sorted.