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. Garryowen, with David Wallace making a return, had two points to spare (12-10) over Belfast Harlequins in Dooradoyle while Cork Constitution came unstuck in Belfield, losing 36-20 to the Students while Terenure College were beaten 40-21 by Galwegians in Lakelands.