A try from centre Jean Vincent Igarza eighteen minutes from time and a Pat McCarthy injury time penalty gave the League leaders an 8-6 win in Eaton Park.
Playing with a strong wind in the opening half Ballymena had just an Ian Humphreys drop-goal and Dirk Strydom penalty to show for their efforts and although they defended resolutely in the second half they were unable to deny the Cork side a victory that keeps them top of the table.
In second place are Shannon who took a six point lead into the second half of their game against Clontarf in Castle Avenue, the scores coming from the trusty boot of Tom Cregan.
With the wind at their backs from the restart, Clontarf launched an offensive that resulted in a try from wing Daire McElligott after just seven minutes, with the conversion from David McAllister edging the home side in front.
'Tarf dominated but were unable to convert that dominance into scores and Cregan landed a 72nd minute penalty to put his side back in front.
Seven minutes later Clontarf were back in the lead when Daire O'Shea scored in the corner for looked like the crucial score. However, Shannon refused to give it up and deep in injury time, centre Brian Touhy made the decisive break to score the winning try that leaves the Limerick side just one point off the leaders.
The two Munster sides have opened up a gap between themselves and the chasing pack. Shannon, on 45 points are 11 clear of third placed Buccaneers who had no game this afternoon and Buccs meet Con in Temple Hill in the next series of matches which are scheduled for the 28th of February. And then, after that (March 13th) Buccs have to travel to Thomond Park to play Shannon. So, if the top two hold their form, they are shaping up meet in the final in May.AIB League Division 1Belfast Harlequins 7-19 Blackrock College Ballymena 6-8 Cork ConstitutionDungannon 17-27 Co. Carlow Galwegians 8-27 Garryowen Lansdowne 29-10 St. Mary'sCollege Clontarf 12-14 Shannon U.C.D. 20-13 Dolphin Buccaneers - Free
AIB League Division 2Barnhall 17-19 UCC Dublin University 18-27 Bective Rangers DLSP 33-20 ThomondMidleton 14-13 UL Bohemians
AIB League Division 3City of Derry 25-11 Ballina Clonakilty 13-13 Greystones Corinthians 8-9 NaasInstonians 22-7 Banbridge Old Wesley 8-13 Ards Portadown 15-16 ConnemaraQueensUniversity 31-5 Suttonians Skerries - Free