Seeing off a familiar foe could prove a tricky challenge for Munster
Death, taxes and a general lack of interest about away trips in Europe from Castres. For two decades the French club have generally focused their attention on domestic matters to the detriment of their Heineken Cup efforts. Could this year be different?
Top 14 champions for the second time in five seasons, they have talked up their approach to this competition.
In round one, they rolled up their sleeves and secured a valuable losing bonus point in Gloucester. A week later, they were reduced to 14 men against the formidable Exeter Chiefs but eked out a remarkable 29-25 win at Stade Pierre Fabre.
They arrive in Limerick this weekend a familiar foe. No two clubs have met more than these two; this will be the 15th renewal of a fixture routinely dominated by the Irish side.
Last season, they drew in France and Munster won well at Thomond Park. At that stage, the visitors' interest in the competition had long since ended; tomorrow could be a different proposition.
If they do turn up, they will make life difficult for a home side looking like European contenders once again.
However, the loss of Jean Kleyn will be felt against a big pack, while James Cronin and Stephen Archer's absence leaves them with inexperienced front-row cover.
Kleyn's ballast is key to Munster's scrum effort, while his work around the park in the tight will be missed. Billy Holland is an able and experienced replacement, while sub Fineen Wycherley is an exciting talent.
Against a team who look to squeeze opponents into submission, patience will be the key for Munster.
But they will need to front up physically above all else to provide Conor Murray and Joey Carbery with the type of possession needed to release a backline laced with threat. Getting Chris Farrell, Keith Earls and Andrew Conway into the game is key.
So, much of the burden will fall on a tight five with plenty of European miles on the clock and a back-row that can match any in Europe.
Last week's win over an understrength Edinburgh was a decent warm-up and, if the home side can reach a similar pitch against a much better opposition, they'll announce themselves as proper contenders.
This six-day back-to-back is an opportunity to take control of a difficult pool ahead of their visit to Gloucester and home decider against Exeter in round six.
Ideally, they'd get to that point having already qualified and their destiny is in their own hands right now.
Discipline will be key given Castres' strong kicking game and excellent lineout maul, while the Reds can limit the threats by keeping hold of the ball and forcing their visitors into a high tackle count.
In Murray and Carbery, they have huge potential and it's all about providing the platform for them to manage the game.
Unlike previous iterations, this version of Castres may not be of a mind to offer it up easily.
- Munster v Castres, tomorrow; Live BT Sport 2, 1.0.