Old Belvedere eased their relegation worries with a 25-13 home win over St. Mary's, which puts the pressure on both Shannon and U.L. Bohemian to avoid the drop.
Bruff's hopes of staying in Division 1B received a major setback when bottom side Ballymena defeated them 29-14 to record their second victory of the season. William Casey scored a try and Brian Carroll kikced three penalties.
In Division 2A both Terenure College and Corinthians won promotion. Terenure defeated Cashel 29-10 at the Tipperary venue.
Tries from James Buckley and Finn Gormley both of which Mick O'Flynn converted and who also added a penalty helped Corinthians to a 17-14 victory over U.C.C. at the Mardyke. Johnny MacCarthy and Dave O'Connell replied with tries for the students and Sean Og Murphy converted both.
Old Crescent eased their relegation worries with a 36-13 away win over Seapoint. Brendan Guilfoyle scored two tries for Crescent and William Hanly, Andy Brace got one each, Kevin Meade contributed a try, penalty and three conversions and Alan Bennie kicked a conversion.
Highfield lost away to Old Wesley 48-15 and Midleton look in grave danger of being relegated following their 72-7 away defeat by City of Derry. Brian Morris scored a try for the East Cork side and Paul Daly kikced two conversions.
Nenagh Ormond kept their faint hopes of promotion from Division 2B alive with a 25-18 away win over Suttonians. Stephen Carey and David Corcoran each scored two tries and Donal Fogarty added a penalty and a conversion.
Thomond were beaten by leaders Rainey Old Boys 34-9. John Lillis kicked three penalties for the Limerick side.
Sunday's Well lost at home to Boyne 10-3 with Shane O'Riordan kicking a penalty for the 'Well.
Clonakilty are now in the relegation place after their 21-15 home defeat by Naas. Kieran Howlin and Tony Illston scored tries for the west Cork side and James Deasy kicked a conversion and penalty.
Ulster Bank League Division 1A: Dolphin 24, Cork Constitution 27;
Lansdowne 32, Clontarf 25;
Old Belvedere 25, St. Mary's College 13;
Shannon 16, Garryowen 12;
Young Munster 0, U.L. Bohemian 6;
Division 1B: Ballymena 29, Bruff 14;
Ballynahinch v Buccaneers postponed
Blackrock College 28, Dublin University 33;
Dungannon 46, Malone 19;
U.C.D. 33, Belfast Harlequins 19;
Division 2A: Cashel 10, Terenure College 29;
City of Derry 72, Midleton 7;
D.L.S.P. 10, Greystones 23;
Galwegians 24, Banbridge 27;
Old Wesley 48, Highfield 15;
Queens University 27, Bective Rangers 39;
Seapoint 13, Old Crescent 36;
U.C.C. 14, Corinthians 17;
Division 2B: Ards 11, City of Armagh 7;
Clonakilty 15, Naas 21;
Connemara 6, Skerries 61;
NUIM Barnhall 50, Navan 14;
Rainey Old Boys 34, Thomond 9;
Sligo 26, Instonians 6;
Sunday's Well 3, Boyne 10;
Suttonians 18, Nenagh Ormond 25;