Shannon were probably left wondering how they lost a game they'd dominated for long periods. They led 7-3 at half-time thanks to a Colm McMahon try and looked home and hosed when they led 13-7 with time almost up. Then, with a minute of normal time remaining Smart scored near the posts and tapped over the conversion for a one point victory.
In Stradbrook, the home side led 13-10 at the break but then imploded as Lansdowne ran in 37 points without reply.
Man of the Match, Matt Leek, edged the visitors ahead with a brace of penalties, then converted Brian O'Mahony's try to start the rout. Another Leek penalty was followed by a try from Liam Toland and Leek rounded off a marvellous personal performance with a late try to bring his personal tally to 27 points.
In general, it was a day of narrow finishes. Co Carlow went down by a single point, 13-12, to Dungannon in Oak Park. There was just two points separating Buccaneers and St Mary's at Moher Road, Buccs winning 20-18.
The leading trio in AIB League Division Two, Dolphin, Old Crescent and Thomond all recorded victories while Young Munster move up to fourth place in the table after winning 15-12 at home to Greystones. Good news from a Munster and Ireland point of view is that Rob Henderson played the entire game for Munsters and according to one source, "just got better and better as the game went on."
Dolphin needed a last gasp winner to see off Dublin University 20-17 while second placed Old Crescent retained their position after winning 19-15 in Malone.
Third placed Thomond won 22-20 at home to Portadown while Bective Rangers lost for the first time at home this season, going down 13-8 to Barnhall. UCC won the Cork derby beating Sunday's Well 15-3 at The Mardyke.
In the top of the table clash in AIB League Division Three, Waterpark and Wanderers drew 20 points apiece at Merrion Road but Wanderers slip to fourth place, overtaken by Instonians who won 49-0 in Skerries and Corinthians who beat Clonakilty 22-13 in Shannonvale.
Highfield were narrow 18-16 winners against Old Wesley at Woodleigh Park, Ballina won 44-19 at home to Banbridge and at the bottom of the table Naas continued their dismal form, losing 15-13 at home to the Connemara All Blacks; City of Derry were beaten 10-7 at home by Queens and Monkstown remain rooted to the bottom desppite sharing the spoils (23-23), with Suttonians at Station Road.