By the time the Munster team bus had returned to Limerick in the wee hours of Saturday morning, those on board were still trying to make sense of their rip-roaring 22-19 derby win in Ravenhill.

Ultimately, Munster got the victory they craved and that it came with the added bonus point made the long journey home all the sweeter, even if there is a stark realisation that major improvements are needed across the board if they are to stand any chance against Leinster at Thomond Park on Friday night.

Their review will be a mixed affair. The quality of Mike Prendergast’s attack and Munster’s four tries was excellent, while Denis Leamy’s defence largely showed up well despite conceding three tries to a 14-man Ulster side that were left with major regrets at not seeing out the closing two minutes, 19-15 in front.

Munster scrambled brilliantly all evening, as they repeatedly held Ulster up over the line, with Gavin Coombes (32 tackles) front and centre of that stand, while his fellow West Cork natives, Fineen Wycherley (27 tackles) and John Hodnett (20 tackles), were also to the fore.

However, Munster will know that they should never have required a last-gasp try from hat-trick hero Tom Farrell to get them out of jail, as Ulster had been playing with 14 men since Tom O’Toole’s red card on half an hour.

After being penalised a whopping 17 times in their poor Champions Cup defeat in Castres a week earlier, Munster had spoken about the need to improve their discipline, yet they conceded another 16 penalties in Belfast.

“We had two headline areas that we focused on and discipline was the first,” Munster interim head coach Ian Costello explained. “Ulster have a good maul and pick-and-go game and we played completely into their hands.

“A lot of that is controllable. Ben (Whitehouse) is a very technical referee and we gave him really easy opportunities to penalise us at times.

“If we had the ball more often, we won’t get pinged so we didn’t hold onto the ball as well as we could have so we put ourselves under a lot of pressure. It’s something we have to address.”

Playing with an extra man should have meant that Munster were able to control the game, but they never got a grip on it, which Ulster deserve a lot of credit for.

“I have to say I really do think it was just the stress they put us under,” said Munster hooker Niall Scannell.

“They held possession for long periods. They didn’t do anything flash, they just picked and went numerous times.

“We did really well to fight them off for a good while but naturally, with pressure, fellas have to make decisions to try and make turnovers and stuff.

“And I just think we didn’t get the bounce of the ball on a lot of them. We held them up a number of times as well but, unfortunately, a couple of them were on the back of already giving away a penalty, so that just added more pressure.

“It’s hard to break that cycle but I think eventually when we did, the backs got us out of trouble. So we both probably did our part in terms of the forwards standing strong and the backs really moving the chains to get us out of that 22.

“But that’s just not a situation that we want to put ourselves in against Leinster.”

And therein lies the scale of the challenge facing Munster. They will at least be able to call on Tadhg Beirne to face Leinster after the captain was rested for the Ulster game, while Peter O’Mahony and Conor Murray are hopeful of being fit. However, Alex Nankivell is understood to be looking at months out rather than weeks with the hamstring injury suffered in the incident involving O’Toole.

Leinster will arrive in Limerick looking to dampen the Christmas mood and, with a stingy defence to break down, Munster can ill-afford to give Leo Cullen’s men as much access into the game on the back of sloppy discipline or unforced errors.

“(We need to be) Infinitely better,” Costello added. “I’ll be guessing by the side they picked (for Connacht on Saturday), there will be lots of rotation for this week.

“We have been tested massively with injuries and we had a few more against Castres. But that’s the beauty of having the likes of Brian Gleeson. He was brilliant when he came on (against Ulster) after a tough night in Castres. Evan O’Connell has come back in fresh and produced a big performance.

“We are going to need all these boys over the next month. And some of them will get an opportunity in Thomond Park against a very strong Leinster side, hopefully in front of a full house.”