In second place, just one point behind are Garryowen who raced into an early 13 point lead against Buccaneers at Dubarry Park before winding up 27-18 winners.
The eagerly anticipated return to competitive action of Munster's John Kelly was delayed when the Cork Constituion's clash with Dublin University at College Park was postponed.
AIB League Division One Galwegians 13-19 UCD; Ballymena 27-31 Shannon; Buccaneers 18-27 Garryowen; Clontarf 8-13 Blackrock College; Co Carlow 26-14 Dungannon; Lansdowne 9-13 Belfast Harlequins; Dublin University P-P Cork Con.
In Division Two Dolphin were held to a 10-10 draw by second placed St Mary's College at Musgrave Park. The home side led 10-0 at the interval thanks to a Mick Manning try and five points from the boot of John O'Mahoney but a converted try in the 78th minute earned the visitors a share of the spoils.
UCC maintained their push for promotion with a 12-3 win over Young Munster at Tom Clifford Park, Frank Murphy and Richard Lane scoring tries for the students while Munster centre MikeMullins was on the mark for Old Crescent, scoring a try in his side's 15-0 win over Waterpark at Rosbrien.
AIB League Division 2. Ballynahinch 16-6 Thomond; Bective Rangers 16-3 Barnhall; DLSP P-P Highfield; Dolphin 10-10 St Mary's College; Midleton 3-0 Malone; Old Belvedere P-P Ul Bohemians;Old Crescent 15-0 Waterpark; Young Munster 3-12 UCC.
AIB League Division 3. Banbridge 5-22 Connemara; Bruff 5-21 Greystones; City of Derry 22-17 Suttonians; Clonakilty 18-7 Dublin University; Corinthians 29-5 Sunday's Well; Instonians 9-15 Ards; Portadown 16-17 Skerries.