Happy Christmas your arse, as Shane McGowan once said.
There was to be no peace this night between these two sets of men.
If it was a Christmas cracker in Limerick then it was in the best bah humbug traditions of Fairytale of New York, Ebenezeer Scrooge and Billy Bob Thornton's brilliantly bitter turn in Bad Santa.
Pretty it wasn't.
Munster will face the New Year in much the higher spirits on the back of it.
This Guinness PRO14 win marked their first against the old enemy in five attempts and brought to an end their run of defeats before it could mushroom from an annoying two into a worrying three.
For Leinster it is a first loss since their one-point defeat away to Toulouse back on October 21st.
There have been occasions in recent years when the flame from this famed rivalry has dimmed but Leinster's locked and loaded team selection gave warning of the visitors' intent for their annual Christmas trip down the motorway.
And old enmities burned brightly throughout a first-half that was pockmarked by a succession of ugly flashpoints, all of which contrasted sharply with the bonhomie that reins when so many of these players convene for duties in the green jersey.
Players on both sides were guilty of stepping over the line but Leinster were by some distance the more culpable of the parties and they would make for the tunnel at half-time 13-3 down.
The game wasn't lost at that point but their discipline had certainly gone missing.
James Lowe had already seen red by then and both props, Tadhg Furlong and Cian Healy, had spent ten minutes in the bin.
Furlong was a lucky boy that his exile hadn't been made permanent but then Conor Murray should have earned a yellow too.
It was the type of occasion that makes for a referee's worst nightmare and maybe all the more so given Frank Murphy, the man in the middle, had already been a pre-game talking point given he had played as a scrum-half for the hosts in days gone by.
Murphy did well to keep a lid on the ferment which started in the early exchanges when Jonathan Sexton grappled with Fineen Wycherley, tearing the latter's scrum cap from his head and flinging it at his face after the Munster lock's thumping tackle.
03: Early warning for Johnny Sexton at Thomond Park.
The Munster fans aren't happy, but the 'correct call' says Stephen Ferris.December 29, 2018
Sexton was stomping around like a bear with a sore head throughout the first 40 and too many of his teammates followed suit, among them Scott Fardy who thundered into Cloete at one point before the flanker had taken possession of the ball.
He paid with a penalty and Munster's opening score.
Justice was seen to be served when Cloete himself rumbled over off the back of a maul from the subsequent lineout inside the Leinster 22 and Joey Carbery landed the conversion to make it 7-0 to Johann van Graan's side with 16 minutes played.
The atmosphere inside Thomond Park was pitching up around febrile by now, thanks in large part to the odd fracas that drew in the vast majority of players, and Healy paid for the general mayhem when getting a yellow for a high tackle on Murray.
Someone had to go. It was his misfortune to transgress at that moment.
The Munster scrum-half should really have suffered the same fate for a similar indiscretion on Jordan Larmour soon after and Furlong should certainly have seen red rather than yellow for a dangerous clearout on Cloete at a ruck on the half-hour.
The Ireland tighthead ran in at pace and caught the Munster man in the head with his chest/upper arm.
Cloete, eventually, left the pitch on a motorised stretcher and in a neck brace.
His game was over and it beggared belief that Furlong's wasn't as well.
Leinster's only cheer until that point was a Sexton penalty to leave the score 7-3 but their task was made considerably harder eight minutes before the break when Lowe was shown to the sheds after making contact with Andrew Conway in the air.
The Leinster wing had pulled out of any contest for the ball at the last second but too late for Conway who somersaulted over his upper body and onto the ground.
It was anything but malicious and yet there was a clear deficit in Lowe's duty of care to his opponent.
He had to go.
Carbery added two more penalties before the break against a Leinster side playing for a time with just 13 men and another three-pointer from the Ireland back-up ten on the restart – his fourth from four kicks – left it 16-3 for the home side with 36 minutes still to play.
A comforting lead, if not a definitive one, and Leinster ate into it inside just four minutes with a try from James Tracy who squirmed over off the back of a lineout maul.
Kudos to Sexton who showed a cool head after his fiery first-half in kicking to the corner twice.
"It doesn't take a scientist to work out that it was discipline that probably cost us the game"December 29, 2018
The game by now had shed its agitation, no doubt on the say-so of the two coaching staffs during the interval, but neither side could find anything like a killer touch.
Both malfunctioned at the lineout and Munster, in particular, lacked creativity going forward.
It took a moment of thievery to set the seal on the win.
Leinster were pummelling away inside the Munster 22 with eight minutes still to go when a loose Ciaran Frawley pass was pounced upon by Keith Earls who hot-footed it for the far end line to make it 24-10 with Tyler Blyendaal's conversion to come.
Frawley had come on for a bemused looking Sexton on 60 minutes in what looked like a pre-planned bout of minute managing but Leinster kept plugging away and finally earned a second try through Max Deegan in injury-time.
A consolation but an insignificant one for the visitors.
"I'm just here to perform for the boys and give it my best"December 29, 2018
Munster: M Haley; A Conway, S Arnold, D Goggin, K Earls; J Carbery, C Murray; D Kilcoyne, N Scannell, J Ryan; J Kleyn, B Holland; T Beirne, C Cloete, CJ Stander.
Replacements: A Botha for Cloete (30); S Archer for Ryan (59); D Sweetnam for Goggin and B Holland for Kleyn (both 65); J Loughman for Kilcoyne and T Blyendaal for Carbery (both 70); A Mathewson for Murray (74); K O'Byrne for Scannell (76).
Leinster: J Larmour; R O'Loughlin, G Ringrose, N Reid, J Lowe; J Sexton, L McGrath; C Healy, J Tracy, T Furlong; S Fardy, J Ryan; R Ruddock, J van der Flier, J Conan.
Replacements: M Bent for Ruddock (36-40) and for Furlong (69); B Byrne for Tracy, P Dooley for Healy and C Frawley for Sexton (all 60); M Deegan for Ruddock (65); C O'Brien for Ringrose (69); H O'Sullivan for McGrath and R Molony for Ryan (both 74).
Referee: F Murphy (IRFU).