Young Munster lost ground in the title race as their three-match winning run was ended by second-from-bottom St. Mary’s College who gave themselves a timely lift with a 21-15 triumph at Templeville Road.
Leinster 'A' out-half Cathal Marsh was Mary's lone scorer on Saturday, landing seven penalty efforts as Peter Smyth's men, who trailed 12-9 at the interval, secured their first win in four league outings.
Third-placed Young Munster erased an early 6-0 deficit, and their Dublin hosts looked in real trouble as they leaked a couple of tries and lost forwards Richie Sweeney and Stephen Bradshaw to the sin-bin.
Ger Slattery's accurate throwing in the lineout provided the platform for two tries from the Munsters pack, as they cancelled out Marsh's opening two place-kicks (10 and 14 minutes).
Crucial too was some expert tactical kicking from the likes of Willie Staunton, Gearoid Lyons and Ben Martin as Mary's were pinned back time and again.
The first Young Munster try saw powerful flanker Yasin Browne crash over on the end of a well-worked lineout maul. Centre Lyons' conversion edged the the Cookies in front at 7-6.
Key man and stand-in captain Sweeney than saw yellow for Mary's, having infringed deep inside his 22. A neat blindside move off the resulting lineout, five metres out, put number 8 Rennison over out wide. The conversion was missed on this occasion.
Despite having lock Bradshaw past the half hour mark, 14-man Mary's won a late penalty in front of Munsters' posts and Marsh obliged to make it a three-point game at the break.
Loose kicking out of hand blunted the Mary's attack on the resumption, but a good kick chase from full-back Ray Crotty forced a five-metre lineout. Frustratingly for the home support, the lineout was won but possession was subsequently turned over.
Smyth's charges came again, with their forwards building some pressure which yielded the levelling penalty from Marsh. A spell of aerial ping pong broke in Mary's favour and another penalty was sent over by their in-form place-kicker for 15-12, with 66 minutes on the clock.
The home side were winning more ball and using it to good effect, with Young Munster continuing to fall foul of referee Leo Colgan's whistle. They had winger Dan Goggin sin-binned and Marsh nailed the three-pointer from the 10-metre line.
Lyons responded off the kicking tee for the Cookies with 10 minutes to go and the sin-binning of Mary's replacement Shaun McCarthy for a scrum infringement left the home side hanging on.
Young Munster were left to rue some further indiscipline, though, as they coughed up what turned out to be the match-winning penalty in the 78th minute – awarded for failing to release at ruck time. Marsh sent the ball sailing through the uprights to complete a hard-earned home victory.
Young Munster head coach John Staunton felt the breakdown was allowed to become a 'free-for-all' in the second half, and he bemoaned the performance of the referee when giving his reaction afterwards.
“There were a lot of controversial refereeing decisions. There should have been at least two penalty tries in the first half but that's water under the bridge. Give Mary's credit, they played like a Young Munster side in the second half,” he told the Irish Examiner.
“We started at 100 miles an hour. We were conscious of our away form and knew we'd have to put in a big shift today. We were over the line twice except for the referee binning two fellas and not giving a penalty try. We created lots of chances but didn't execute them.”
Staunton added: “I'm not taking away from their victory but I would question the interpretation of the referee with the tackle-release rule. You tackle, release and then compete but that wasn't in operation at all. Because the breakdown became a free-for-all in the second half, Mary's ploughed in and stopped us from playing.
“We couldn't recycle the ball because the tackler wasn't releasing. He didn't referee the sides of rucks at all. But we had chances to rectify that. If the referee isn't doing it, you sort it out yourself.”
Referee: Leo Colgan (IRFU)