Replacement fly half Michael Glancy kicked a drop goal two minutes into injury-time as Belfast Harlequins pipped their Ulster rivals Ballymena, 21-20, at Deramore Park.
AIB LEAGUE: DIVISION ONE: Saturday, January 28
BELFAST HARLEQUINS 21 BALLYMENA 20, Deramore Park
Scorers: Harlequins: Jonny McCalughlin, Darren Cave; Con: McClaughlin; Pens: Nopera Stewart, Michael Glancy; Drop: Glancy
Ballymena: Tries: Scott Young, Henry Head; Cons: Paddy Wallace 2; Pens: Wallace 2
'Quins are just a point away from the top four after a last gasp win.
Ballymena led 17-3 early on thanks to tries from winger Scott Young and lock Henry Head. Paddy Wallace converted both efforts and landed a penalty.
But 'Quins reduced the gap to two by the break with Ireland Under-21 centre Darren Cave and winger Johnny McClaughlin both touching down.
Wallace and Glancy swapped penalties in the third quarter before the latter ensured a home win.
ST. MARY'S COLLEGE 31 DUNGANNON 10, Templeville Road
Scorers: Mary's: Tries: Jonathan Sexton 2, Adrian Copeland; Cons: Sexton 2; Pens: Sexton 4
Dungannon: Try: Andy Hughes; Con: Gareth Steenson; Pen: Steenson
St Mary's fly half Jonathan Sexton scored 26 points as the Dubliners got the better of Dungannon at Templeville Road.
Sexton, who has been named in the Irish squad for this Friday's U-21 6 Nations opener against Italy in Athlone, scored two tries, one in either half, two conversions and four penalties in a brilliant display.
Flanker Adrian Copeland also notched a first half try to help Mary's lead 21-3 at the break.
Former Under-21 international Gareth Steenson had kicked a penalty for 'Gannon and he converted captain Andy Hughes' late try.
The win brought to an end Mary's two-game losing streak.
COUNTY CARLOW 9 CORK CONSTITUTION 20, Oak Park
Scorers: Carlow: Pens: Greg Jacob 2, Billy Murphy
Cork Con: Tries: Frank Cogan, Brendan Cutriss; Cons: Daragh Lyons 2; Pens: Lyons 2
Captain and number 8 Frank Cogan put in a talismanic performance to help Cork Constitution back to winning ways in the midlands.
Con have lost recently to all three of their main play-off rivals - Clontarf, Shannon and Garryowen - but tries in either half from Cogan and flanker Brendan Cutriss helped stop the rot.
Cogan's score, ten minutes into the opening half, saw him dive over off the back of a scrum to help Con lead 10-3 at the break - Carlow centre Greg Jacob and Con number 10 Daragh Lyons traded penalties.
Winger Billy Murphy and Jacob added further penalties for the hosts, but Cutriss' try from a clever Con shunt forward condemned Carlow to their ninth straight defeat.