Castres 13 Munster 12
Munster were unable to make it a clean sweep of Irish wins for the second weekend-in-a-row when they came up just short in a bruising encounter in Castres.
The citing officer may have to take a look at a couple of possible eye-gouging incidents but that will be scant consolation to Munster this evening as they fly home from Toulouse.
The bonus point though could, as always, prove invaluable when the pools are decided next month.
Exeter’s win in Gloucester on Friday night ensured that Munster were going to top the pool over Christmas regardless of how this encounter went.
The incessant rain throughout the afternoon in Castres made handling difficult and both sides struggled to build the phases in the opening quarter.
Neither side looked like manufacturing a try in that time but Munster built up a 6-3 lead after 20 minutes.
Joey Carbery, partnering Conor Murray for the first time, landed a good penalty from 45 metres after three minutes for an excellent start.
Benjamin Urdapilleta was off target with his first penalty - after Munster were pinged in their first scrum - but the Argentine made no mistake on 11 minutes after hooker Niall Scannell was penalised for a high hit on Castres fullback Scott Spedding.
Carbery missed his next penalty from inside halfway but then landed a more difficult kick from the left after Castres flanker Yannick Caballero was penalised for a hit on Munster captain Peter O'Mahony.
Castres took over from there and pounded the Munster line with a series of drives and they were rewarded when loosehead Paea Fa'anuna was adjudged to have grounded the ball despite the best efforts of Tadhg Beirne.
Urdapilleta converted to push Castres 10-6 in front after 24 minutes, with Spedding then off target with a penalty from inside his own half.
Tempers rose as the exchanges intensified with O'Mahony claiming to referee Wayne Barnes that Chris Cloete had been gouged, while Sammy Arnold made a similar claim to the referee as the teams went in at the break.
Munster had opportunities to cut the gap before the break but Carbery failed to find touch with a penalty from halfway.
And then in the final attack Munster forfeited three points from a penalty in front of the posts for a tap and go which was turned over after Castres scrum-half Rory Kockott was binned for deliberately killing the ball as Murray tried to feed from a ruck a couple of metres short of the home line.
That left it 10-6 at the break with Castres, needing to win to have any chance of making it to the knockout stages for only the second time in 15 attempts, down to 14 men for almost ten minutes after the restart.
Castres replaced both props at the break but they were given a baptism of fire in the first scrum when Munster drove them back and won a penalty on a home put-in, but Carbery missed from 39 metres in front of the posts.
There was a further set-back for Munster after 48 minutes when Castres stole a lineout after a penalty down the left to the 22.
But Munster maintained their composure. Carbery went for distance inside the 22 with a third penalty in quick succession. This time CJ Stander took the ball at the back of the lineout and when Castres collapsed the maul, Carbery made no mistake with the penalty to cut the gap to 10-9 after 51 minutes.
But that score was cancelled seven minutes later when Munster failed to execute an exit from their 22 cleanly and Niall Scannell was binned for bringing down a maul.
Murray had a chance to cut the gap to the minimum four minutes later when he attempted a penalty from 47 metres but it never looked like making the target.
But the pressure yielded an easier penalty and Carbery landed his fourth kick to make it 13-12 with 14 minutes remaining in the contest.
Munster supporters thought Andrew Conway had got in for their first try when he chased his own chip but television replays showed he knocked on as he tried to slide over with Urdapilleta challenging.
Munster, though, were awarded a penalty from 40 metres on the right after a late tackle on Stander during the same move but Carbery missed the target.
Castres were reduced to 14 men for the closing ten minutes when replacement hooker Marc-Antoine Rallier was binned for that challenge on Murray.
However, Munster weren’t able to capitalise and they coughed up a penalty on their own scrum and then lost a lineout on halfway as Castres held on for victory.
Scorers - Castres: P Fa'anunu try, B Urdapilleta 2 pens, con
Munster: J Carbery 4 pens
Castres: S Spedding; M Laveau, T Combezou, F Vialelle, T Paris; B Urdapilleta, R Kockott; P Fa'anunu, K Firmin, M Clerc; T Lassalle, L Jacquet; Y Caballero, M Babillot (c), M Vaipulu. Replacements: A Tichit for Fa'anunu (h-t), W Hounkpatin for Clerc (h-t), C Samson for Lassalle (60), R Ebersohn for Vialelle (61), J Radosavljevic for Kockott (60), M A Ralier for Firmin (67), K Gimeno for Caballero (71), K Firmin for Paris (73).
Munster: M Haley; A Conway, S Arnold, R Scannell, K Earls; J Carbery, C Murray; D Kilcoyne, N Scannell, J Ryan; T Beirne, B Holland; P O'Mahony (c), C Cloete, CJ Stander. Replacements: A Botha for Cloete (55), K O'Byrne for Botha (61-66), S Archer for Ryan (64), JJ Hanrahan for Carbery (73), J Loughman for Kilcoyne (75), F Wycherley for Holland (76).
Referee: Wayne Barnes (RFU).