Hello and welcome to the first of today’s Champions Cup liveblogs.

Leinster host Castres at the RDS. Kick-off is at 3.15pm and the game is live on BT Sport.

I’ll be guiding you through all of the action over the next couple of hours. As per usual, feel free to get in touch via Twitter, Facebook or the comments section below.

A bit of pre-match reading for you here:

• ‘It’s hard to know if the Pro12 has been preparing us’ – Leinster turn to Europe

• ‘We rely on bringing guys through the academy’: Cullen confident Carbery can fill Sexton’s boots

And here’s a reminder of the Leinster team — Johnny Sexton misses out with a hamstring issue. It’s a massive day for Joey Carbery.

15. Rob Kearney
14. Zane Kirchner
13. Garry Ringrose
12. Robbie Henshaw
11. Isa Nacewa (captain)
10. Joey Carbery

9. Luke McGrath
1. Jack McGrath
2. Sean Cronin
3. Tadhg Furlong
4. Devin Toner
5. Ian Nagle
6. Rhys Ruddock
7. Josh van der Flier
8. Jamie Heaslip

Replacements:
16. James Tracy
17. Cian Healy
18. Mike Ross
19. Ross Molony
20. Dan Leavy
21. Jamison Gibson-Park
22. Cathal Marsh
23. Noel Reid

This is how Castres will be lining out:

15. Geoffrey Palis
14. Remi Grosso
13. Thomas Combezou
12. Robert Ebersohn
11. David Smith
10. Benjamin Urdapilleta
9. Antoine Dupont

1. Antoine Tichit
2. Jody Jenneker
3. Daniel Kotze
4. Victor Moreaux
5. Rodrigo Capo Oretga
6. Mathieu Babillot
7. Steve Mafi
8. Alex Tulou

Replacements:

16. Brice Mach
17. Mihaita Lazar
18. Damien Tussac
19. Thibault Lassale
20. Anthony Jelonch
21. Rory Kockott
22. Maxime Javaux
23. Florian Vialelle

Today’s referee is Matthew Carley from England.

Conditions in Dublin are excellent for some free-flowing rugby, here’s hoping we get some.

Get your predictions in now, or forever hold your piece.

Bonus-point win for Leinster for my money.

The teams have played three times before, and it isn’t pretty reading for Castres:

• 17/1/15 Leinster 50 Castres Olympique 8
• 26/10/14 Castres Olympique 16 Leinster 21
• 12/1/14 Castres Olympique 22 Leinster 29

The French side have made a disappointing start to their Top 14 season — they’re in 11th position after eight games having lost four matches, drawn one and won three.

Leinster, on the other hand, have impressed in their Pro12 campaign, winning five of their opening six fixtures to sit in second spot on points difference.

Tommy Dickson / INPHO Tommy Dickson / INPHO / INPHO

The RDS is looking well ahead of the game. Just 30 minutes until kick-off.

In other news, Wasps have destroyed Zebre with an 82-14 win in Connacht’s pool.

The teams are coming out on to the field. Running a few minutes behind schedule.

And we’re off at the RDS

It’s been a lively start. First scrum of the day to come on halfway, Leinster with the put-in.

Joey Carbery showing no signs of nerves, has already had a couple of good kicks from hand and some nice, flat passes.

Nacewa is lining up a kick at goal after a high tackle on Cronin.

But the Leinster captain drags it to the left and wide. It was tricky enough.

Great break from Leinster but they lose the ball into touch just metres short of the Castres line.

The home side have been truly dominant in the game’s early stages.

Leinster 5 Castres 0 (Cronin)

The hosts make their sustained period of pressure count. Having opted to kick to the corner with a penalty in the Castres 22, their lineout maul does the job and Cronin gets over in the left corner. Nacewa failed to add the extras from the touchline.

Castres are having their best spell of the game, which wouldn’t be hard to be fair.

They’re retaining the ball well but struggling to make inroads against a stubborn Leinster defence.

Castres are showing a bit of resilience. Leinster batter and batter again but can’t get over the line and the ball is eventually turned over by a knock-on.

And the rain is back

Castres have settled in to this a bit now, largely on the back of a solid set-piece.

Dan Sheridan / INPHO Dan Sheridan / INPHO / INPHO

Joey Carbery has seen plenty of the ball in the first quarter.

We’re having a lot of stoppages at the moment, scrum after scrum and it’s draining the life out of the game.

Leinster win a penalty against the head, Furlong getting the plaudits.

Clever kick from Nacewa earns his side a great attacking lineout opportunity.

Leinster 10 Castres (Cronin ’26)

Leinster 12 Castres 0

Two attacking lineouts, two mauls, two tries for hooker Sean Cronin.

He broke from the maul about 5m out and did brilliantly to get the ball over the line. Nacewa adds the extras.

Leinster 12 Castres 3

Penalty for Castres for a high tackle. That was all set up by a lovely Dupont break. He looks like quite the talent.

Urdapilleta makes no mistake from straight in front.

Castres are pinged in their 22 for offside. They may be straight in front of the posts but Carbery goes for touch. Cronin on a hat-trick remember.

Leinster 17 Castres 3 (J McGrath ’33)

Leinster 19 Castres 3

On his 100th appearance for the province it’s Jack Mcgrath who gets over. Castres are really struggling with Leinster’s maul game. Nacewa converts to put 16 between the sides.

Urdapilleta kicks a penalty wide for the visitors with half-time approaching.

Ross on for Furlong as a blood sub.

Dan Sheridan / INPHO Dan Sheridan / INPHO / INPHO

HT: Leinster 19 Castres 10 (penalty try ’40)

Castres try an attacking lineout maul of their own and get themselves a penalty try. Game on.

Luke McGrath pinged for coming in from the side and gets a yellow card for his troubles.

Leinster will be wondering how they are only nine points ahead after such a dominant display.

And they’re without their scrum-half for the first nine minutes of the second half. A crucial period in this match coming up shortly.

We’re back under way at the RDS.

Great restart from Toner gets us going.

Nacewa is playing at scrum-half in the absence of McGrath.

Leinster have started this half with real intent but they are undone by a terrific steal.

Leinster get out of a tight spot with an excellent choke tackle. Good work by van der Flier.

Scrum penalty for Leinster and Carbery takes us back to halfway.

TRY: Leinster 26 Castres 10 (Nacewa ’48)

What a footballer this man is. Nacewa spot a gap and fends off a couple of Castres defenders to get the ball down and secure a bonus point for Leinster.

Brilliant for 14-man Leinster with McGrath due back in 30 seconds.

Luke McGrath is back on the field. Nacewa going back to his more familiar surroundings on the wing.

Cian Healy replaces Jack McGrath and James Tracy is on for Cronin.

Leinster win a scrum against the head in the Castres 22. Healy, Tracy and Ross making a statement.

Lineout maul coming up you’d imagine.

Another penalty for Leinster in the Castres 22. Quick tap from Carbery but Castres respond well.

Great break from van der Flier gets Leinster just short of the try line but Castres somehow manage to turn the ball over.

Gibson-Park is now on for McGrath.

Castres have hardly had a sniff in the second half but Leinster can’t get themselves out of sight.

Leinster have another penalty five metres out. They take a scrum on this occasion. makes sense as Castres have just been reduced to 14 men following the sin-binning of Thibault Lassale.

Castres repeatedly infringing. Penalty try surely only another one or two misdemeanours away.

TRY: Leinster 33 Castres 10 (penalty try ’65)

The referee loses patience with Castres and awards the penalty try to the hosts. That’s the five-point victory all but secured now.

An excellent sustained period of pressure from Leinster. It wasn’t pretty but got the job done.

TRY Leinster 33 Castres 15 (Jelonch)

Replacement Anthony Jelonch gets over for the visitors. Just over 10 minutes to play.

Reid, Marsh and Molony are also on the field.

A beautiful break from Carbery nearly results in a beaut of a try but a forward pass ends the move. He’s been excellent today, a real joy to watch.

FT: Leinster 33 Castres 15

They’ll take that. Five points on the board and the likes of Carbery will come on loads for that run out.

Onwards and upwards from here.

Match report and reaction to follow.

Thanks for joining us.

Get yourself a cup of tea and Connacht will be on before you know it.