Ulster Under-20 player Owen McMurray kicked two penalties as Instonians edged past Corinthians to join Ballynahinch at the top of the AIB League Division Three table.
McMurray bisected the posts twice at Shaw's Bridge as 'Inst picked up a 6-3 win. Ballynahinch were prevented from securing their sixth straight win of the league run as their clash with Bruff was postponed due to the bad weather.
The only other postponement in the third tier came in Clifden where the Connemara v Wanderers fixture also fell foul of the weather. Refixture dates have yet to be confirmed.
Elsewhere, Banbridge moved menacingly up to fourth in the standings as centres Alan Gibson and Gareth Martin both touched down in their 18-6 defeat of Portadown at Rifle Park. Martin, an elusive runner, has now scored six tries in as many games.
Mark Banford booted 11 points as Ards pipped hosts City of Derry by 21-19 at Judge's Road - it was Ards' third win in four league games and moves them up to eighth.
At Donnybrook, Old Wesley scored a 22-7 win over Waterpark with centre Brian Doherty, winger Mark Heap and back rower Johnny Ennis all crossing the visitors' whitewash.
The battle of Rainey Old Boys and Nenagh Ormond, the two sides who have been promoted via the All-Ireland round robin series in the past two seasons, went the way of the Tipperary men who triumphed 20-19.
Winger Kevin O'Meara, centre and captain Trevor Powell and hooker Ian Ryan were the try scorers for Nenagh.
Meanwhile, winger Michael Barker took his try tally for the league to seven as he bagged a hat-trick in a 36-25 win for Queen's at Sunday's Well.
DIVISION THREE - SATURDAY'S RESULTS:
Banbridge 18 Portadown 6, Rifle Park
Bruff - Ballynahinch -, Kilballyowen Park (match postponed)
City of Derry 19 Ards 21, Judge's Road
Connemara - Wanderers -, Monastery Field (match postponed)
Instonians 6 Corinthians 3, Shaw's Bridge
Old Wesley 22 Waterpark 7, Donnybrook
Rainey Old Boys 19 Nenagh Ormond 20, Hatrick Park
Sunday's Well 25 Queen's University 36, Musgrave Park