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Johnny Matthews has become Glasgow's Erling Haaland. Unstoppable, irrepressible, inevitable.

The hooker blasted over for an incredible five tries in the last-16 demolition of the Dragons.

Plenty of his tries come from mauls, of course, but one of them was a frantic 20m dash set up by fellow front-row forward Allan Dell.

Matthews is now the Challenge Cup's joint-top try scorer, with only flying wingers Josh Adams, a Lion, and Jiuta Wainiqolo, an Olympic gold medallist, matching him on six touchdowns.

The hooker has 12 tries this season, giving him an average of one per 49 minutes.

Across his 51-game Glasgow career, his record is a try per 64 minutes. Astonishing numbers.

Matthews is on the bench today but don't bet against him burnishing that prolific haul.

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These pair did battle at a rain-soaked Scotstoun just a fortnight ago.

The weather made for an attritional - and largely forgettable - encounter, two teams who love to attack forced to adopt more industrial strategies.

Glasgow did enough to edge it 12-9, with tries from Sione Vailanu and Fraser Brown.

The last time the teams met in Llanelli, though, Scarlets gave the Warriors a pasting, winning 35-10 last March.

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Glasgow made an up-and-down start to life under Franco Smith, formidable at home, feeble on the road.

Since losing to Leinster at the RDS in late November, though, the Warriors have won 15 games out of 17.

The only blots on their copybook came in a rearranged URC trip to Johannesburg, when a depleted squad lost to the Lions, and in this competition, when they were held to a draw by Bath in January.

Gareth Griffiths
BBC Sport Wales at Parc y Scarlets

It is very rare these days to see all four stands open here at Parc y Scarlets.

After such a turbulent season in Welsh rugby, it is a welcome sight with more than 13,000 expected.

The last capacity crowd here in Llanelli was a Heineken Champions Cup match against La Rochelle in 2018.

Welsh regional rugby desperately needs more occasions like this.

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Flying Glasgow winger Sebastian Cancelliere makes a timely return from injury this week. The Argentine last played in a win over Dragons in late January, but has been an outstanding attacker.

When fit, Cancelliere topped the United Rugby Championship charts for metres made, clean breaks and defenders beaten.

Captain Kyle Steyn, full-back Ollie Smith and Sione Tuipulotu are all back in the mix after having their workloads managed in recent weeks.

But Richie Gray is a late withdrawal, meaning JP du Preez starts in the second row and Ryan Wilson comes onto the bench.

Glasgow: Ollie Smith: Sebastian Cancelliere, Sione Tuipulotu, Stafford McDowall, Kyle Steyn (capt); Tom Jordan, George Horne; Jamie Bhatti, George Turner, Zander Fagerson, Scott Cummings, JP du Preez, Rory Darge, Sione Vailanu, Jack Dempsey.

Replacements: Johnny Matthews, Nathan McBeth, Simon Berghan, Ryan Wilson, Lewis Bean, Matt Fagerson, Ali Price, Duncan Weir.

Check this out. Some intrepid Glasgow fans are travelling from Lossiemouth in Northeast Scotland all the way to Llanelli today.

It's a journey of over 550 miles and their sat nav reckons more than 10 hours behind the wheel will be required!

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Ken Owens, fondly known as the Sheriff of Carmarthen, is wearing his customary number two jersey today.

A hugely important player for the Scarlets and Wales.

Image source, Huw Evans Picture Agency

There will be no Parc y Scarlets adieu for Leigh Halfpenny, the great Wales and Lions full-back, as he is left out of the squad for today's semi-final.

Halfpenny is leaving the region at the end of the season, but having only just recovered from a brain injury, doesn't feature tonight.

Instead, Dwayne Peel plumps for rangy alternative, Johnny McNicholl, in the number 15 jersey.

Scarlets: Johnny McNicholl; Steff Evans, Joe Roberts, Johnny Williams, Ryan Conbeer; Sam Costelow, Gareth Davies; Wyn Jones, Ken Owens, Javan Sebastian, Morgan Jones, Sam Lousi, Josh Macleod (capt), Dan Davis, Vaea Fifita.

Replacements: Shaun Evans, Kemsley Mathias, Sam Wainwright, Carwyn Tuipulotu, Iestyn Rees, Kieran Hardy, Dan Jones, Ioan Nicholas.

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Richie Gray made his Glasgow debut against Ulster some 14 years ago and tonight, was due to hit the century mark for his boyhood club.

Now 33, Gray has gone deep into the Champions Cup with Toulouse, and won the Top 14 on his French sojourn in between two Glasgow stints. He also graced the Premiership with Sale Sharks and represented the rugby-obsessed town of Castres.

But, having been named to start in the Warriors second-row, the giant lock has been ruled out 45 minutes before kick-off through illness.

It means JP du Preez will start alongside Scott Cummings, and club icon Ryan Wilson - who is leaving at the end of the season - comes onto the bench.

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Parc y Scarlets has become a stronghold for the West Walians as this season has gone on.

A shaky start saw them lose two and draw one of their opening three home games, but only mighty Leinster have won here in the Scarlets' past 10 home fixtures.

Sharks, Bulls, Edinburgh and an international-laden Clermont are among the scalps that have been claimed along the way.

As of yesterday, the region had sold over 12,000 tickets for the semi-final, just a couple of thousand short of the ground's capacity, and way more than turn out most weekends.

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This is an historic day for both teams.

Scarlets have been in the Champions Cup semi-finals four times before, in 2000, 2002, 2007 and 2018.

But this is the first time they have made it this far in the Challenge Cup, and gives them a great opportunity to claim a European trophy.

The Warriors have never made it to these rarefied surrounds in either European tournament, and hope to continue blazing a tartan trail.

For one of these teams, a first European final awaits.