TICK TOCK, TICK TOCK. That’s the sound of the World Cup clock and you can be sure it’ll be heard in Andy Farrell’s sitting room when he flicks the TV on this evening and has a look at what Jack Carty and Joey Carbery are up to in Limerick (live RTE2, kick off 7.35pm).

Of all the sub-plots surrounding this first derby of the season, none is more fascinating than this battle between Johnny Sexton’s understudies. By now, everyone had predicted that the old stager would have drifted away, that Carbery would have assumed his mantle, that the debate would be over.

Instead it’s raging louder than ever. Sexton may be 36 but he’s still the best No10 Ireland have to offer. Of the rest, Carbery and Harry Byrne have been hit by injuries, Carty by a crisis of confidence. Ross Byrne, meanwhile, is considered too conservative, Billy Burns too ordinary, Ben Healy too young.

And yet the door remains ajar. Everyone knows Sexton can’t go on forever; everyone knows he’ll be 37 when the next World Cup kicks off. Everyone knows Ireland have three Tests next month and the opportunity is there for someone, anyone, to make their mark in the next couple of weeks and leave Farrell with no choice but to start them against Japan and Argentina.

So tonight is audition time for Carty and Carbery who have both had their moments this season but who both have more in the tank.

Carty in action for Connacht last week. Ryan Byrne / INPHO Ryan Byrne / INPHO / INPHO

Deliver here and their chance will come. Deliver here and the result might come, too.

For Munster, especially for Johann van Graan, a point is bound to arrive soon when he gets irked by the narrative he is forced to read. They’re three from three, with three bonus points attached and yet wins over Sharks and Stormers were accompanied by asterisks. “Ah but their forwards scored most of the tries. That’s all fine and dandy against the URC but when until the big boys come at you.”

Next they beat the Scarlets. Or rather, next their B team beat the Scarlets. Again, you had to read the small print. “But the Scarlets were shocking.”

Yes, they were. But Munster weren’t.

The truth is they have been the most impressive side in the competition so far. Their kids are coming through; Craig Casey and Fineen Wycherley are already stars; Ben Healy is fast becoming one; while the sight of those wingers bursting down the sidelines last weekend made you think that this is the best depth Munster have had in over a decade.

Yet every silver lining has its cloud. RG Snyman went off hurt against Scarlets, his knee gone, another operation needed, a world class talent removed in a second.

You suspect this will cost them over the course of the season.

But then you look at everything that is going right for them. The youngsters – we haven’t even mentioned Thomas Ahern yet – they’re shining; the regular Joes (Niall Scannell, John Ryan, Jean Kleyn, Jack O’Donoghue, Mike Haley) are playing really well; Simon Zebo is back, Gavin Coombes is back at last season’s level. Between them, that latter pair offer a poacher’s threat.

Simon Zebo is back in form in Munster red Dan Sheridan / INPHO Dan Sheridan / INPHO / INPHO

You sense then that this could be tough for Connacht.

And yet we’ve been had this conversation before about Andy Friend’s side. When written off, they tend to deliver. Think Leinster away, Ulster away and, indeed, Munster away last season; think Bulls at home this term.

“We need to bring our A Game,” said Friend earlier this week.

Well, Bundee Aki will help in this regard. His return from a prolonged summer break, Sammy Arnold’s return to the starting XV will provide the freshness their midfield needs; John Porch’s return to their back three provides a solidity that frankly wasn’t there against Dragons while Mack Hansen’s super form gives them real threat going forward.

You know tonight’s breakdown battle will be a fierce one when you see the respective backrows. Chris Cloete was superb last week in Llanelli; Peter O’Mahony was immense in the first couple of weeks while Coombes is on course to become an Ireland starter by the end of this season.

Ignore Connacht’s threat at your peril, though. Cian Prendergast has been Connacht’s best player this season; Conor Oliver and Paul Boyle are two of Irish rugby’s most underrated ones. You also know that Ultan Dillane will be up for this, that Finlay Bealham and Dave Heffernan have shown superb form so far this season, that Connacht, basically, aren’t coming to Limerick to make up the numbers.

Expect a big show from them. Expect this to be a lot closer than the bookies have suggested. But can we realistically expect an away win on a night when the crowd will be emotionally charged on the fifth anniversary of Anthony Foley’s passing? The answer is no. Munster to win.

Munster Rugby: Mike Haley; Andrew Conway, Keith Earls, Rory Scannell, Simon Zebo; Joey Carbery, Craig Casey; Dave Kilcoyne, Niall Scannell, John Ryan; Jean Kleyn, Tadhg Beirne; Peter O’Mahony (CAPT), Chris Cloete, Gavin Coombes.

Replacements: Diarmuid Barron, Jeremy Loughman, Stephen Archer, Fineen Wycherley, Jack O’Donoghue, Neil Cronin, Jake Flannery, Dan Goggin.

Connacht Rugby: Tiernan O’Halloran, John Porch, Sammy Arnold, Bundee Aki, Mack Hansen, Jack Carty (CAPT), Caolin Blade; Matthew Burke, Dave Heffernan, Finlay Bealham, Niall Murray, Ultan Dillane, Cian Prendergast, Conor Oliver, Paul Boyle.

Replacements: Shane Delahunt, Greg McGrath, Jack Aungier, Eoghan Masterson, Abraham Papali’i, Kieran Marmion, Jarrad Butler, Tom Daly.

Referee: Chris Busby (IRFU)