But it was a costly first 40 for the men in red as prop Dian Bleuler failed a HIA after a poorly executed tackle on Jack Goodhue and even more concerning was Ireland international scrum half Craig Casey having to be carried off after taking a blow to his knee in the build-up to the hosts' second try.

The second half was less than five minutes old when Castres were a man down again thanks to wing Geoffrey Palis' deliberate knock on. However, not only did Munster fail take advantage, but their scrum was annihilated to concede a penalty and Fernandez made no mistake with the kick this time to move his side 13-7 up.

Munster's night continued to worsen on the injury front as Peter O'Mahony pulled up lame on his heavily strapped right ankle and left the pitch on 55 minutes, shortly after joined in an early exit by Abrahams who was hit with a no-arms shot by Papalii.

However, it looked as though the tide was turning for the visitors when, after Julien Dumora missed another kick, replacement prop Nicolas Corato became the third man in navy blue to be binned after persistent maul infringements with less than a quarter of an hour to go.

Munster made their man advantage count this time and it was Hodnett again as he burrowed over from close range.

The try survived a TMO review for a potential knock on and Crowley kept his nerve amid the noise from the home support to edge his side in front for the first time at 13-14 with 10 minutes to go.

Prendergast would have been hoping that his team could see out the game for a smash-and-grab win, but another scrum penalty saw them cough up their lead as Le Brun became the third Castres player to place the ball on the tee and he split the poles on 74 minutes.

Munster kept fighting right to the end but the final play ultimately summed up their frustrating night as, with the clock in the red, a penalty was given right on halfway in the middle of the pitch.

Crowley tried to get every inch out of the kick but it was acrobatically kept in by Palis, who launched the ball into the stands to cue celebrations for most inside the stadium.

Munster return to URC action next Friday and visit the Kingspan Stadium to take on Ulster in the first of the festive derbies.