O'Sullivan's 79th-minute second was crucially converted by fly-half David Connellan as John McKee's men moved out of relegation trouble with a 17-16 success.

Shane Whelan had kicked the second-from-bottom Dubliners - without a win since January - into an early lead, and the scrum-half also converted lock Alan Maher's touchdown on the half-hour for a 10-5 break buffer.

O'Sullivan was Buccs' initial scorer - notching the westerners' 300th league try in all, in reply.

On the restart, Lansdowne looked to take a hold on proceedings but although Whelan successful with two more penalty attempts, Connacht lock Pieter Myburgh was allowed in for a second Buccs try.

Centre O'Sullivan made Lansdowne pay further for allowing the visitors back into it, as he ended a sizzling 40-metre run, dummying past Lansdowne full-back Johnny Murphy, to set up a grandstand finish.

Connellan arched over a brilliant touchline conversion, and with both Whelan and Andy Tallon wayward with two drop goal attempts in injury time, Buccs held on to move up to eighth.

AIB League Results: Saturday, March 5

DIVISION ONE:

Lansdowne 16 Buccaneers 17, Lansdowne Road Scorers: Lansdowne: Try: Alan Maher; Con: Shane Whelan; Pens: Whelan 3 Buccaneers: Tries: Paddy O'Sullivan 2, Pieter Myburgh; Con: David Connellan

DIVISION TWO:

Ballynahinch 6 Dolphin 26, Ballymacarn Park De La Salle Palmerston 0 Young Munster 16, Kilternan Highfield 13 St Mary's College 13, Woodleigh Park Midleton 6 Bective Rangers 11, Towns Park Old Crescent 27 Old Belvedere 19, Rosbrien Terenure College 12 UL Bohemian 39, Lakelands Park Thomond 33 Waterpark 15, Fitzgerald Park UCC 25 Barnhall 19, The Mardyke

DIVISION THREE:

Ballina 10 Ards 38, Heffernan Park Banbridge 12 Suttonians 25, Rifle Park Bruff 34 Skerries 15, Kilballyowen Park City of Derry 22 Wanderers 12, Judge's Road Connemara 3 Sunday's Well 13, Monastery Field Corinthians 13 Queen's University 8, Corinthian Park Instonians 41 Old Wesley 6, Shaws Bridge Portadown 8 Clonakilty 33, Chambers Park