TITLE challengers Young Munster were made to fight hard before edging bottom side Old Belvedere 19-18 at Anglesea Road.
Belvo had a chance of a first victory of the campaign but Aidan Wynne's late penalty drifted wide.
Young Munster had led 13-0, with tries from Darragh O'Neill and Mark Doyle and a penalty from Willie Staunton. But Belvo hit back with tries from Danny Riordan and Stephen Crosbie, both of which were converted by Wynne.
After Staunton and Wynne exchanged penalties, they were 18-16 ahead going into the closing stages, but Staunton's drop goal won it for Munsters.
Their losing bonus point narrowed the gap to second-from-bottom Blackrock College to five points.
Belfast Harlequins remain on top in Division 1B despite losing 37-30 at Buccaneers. The hosts scored five tries through John O'Brien, Mark McCrea, Paul Harte, Eoghan Grace and Conor Levelle to move up to third in the table.
But Harlequins picked up two points, scoring four tries themselves and losing by just seven. They are now five points ahead of second-placed Ballymena who also lost, 27-13 at home to UL Bohemians.
UL Bohs are still very much in the promotion race in fifth. Wing Finbarr Aherne got two tries.
Fourth-placed Ballynahinch lost 13-8 at Bruff. John Shine's try proved the difference.
Galwegians beat UCD 38-17 at Crowley Park. Tadhg Leader scored two tries and landed four conversions.
Galwegians, Bruff and UCD are all on 27 points, with UCC 13 points adrift. Although the Cork students gave one of their better performances, they still went down 37-27 to Dungannon at the Mardyke.
Trinity lead Division 2A by 11 points after a 49-15 win over Instonians. Second-placed Seapoint beat Clonakilty 35-15.
Cashel's 100pc record came under serious scrutiny at Barnhall, but the Tipperary men escaped with a 25-24 win.