Blackrock College 41 Shannon 27
Blackrock College caused the shock of the day as they bossed Shannon into submission at Stradbrook.
Winger Shane Monahan's hat-trick of tries steered 'Rock to their fourth win in 15 AIB League meetings with the Limerick giants.
Wind-backed Shannon led 22-20 at half-time, with Tadhg Bennett kicking 14 points.
The game was squared up at 27-all courtesy of tries from Simon Morrissey and Richie Mullane, with Bennett missing the conversion.
However, two more scores from Monahan helped the hosts avenge last season's AIB Cup final defeat.
Scorers: Blackrock College: Tries: Shane Monahan 3, Darragh Fitzpatrick, Niall Morris, Simon Morrissey; Cons: Darragh Fitzpatrick 4; Pen: Darragh Fitzpatrick
Shannon: Tries: Stephen Kelly, Richie Mullane; Con: Tadhg Bennett; Pens: Tadhg Bennett 4; Drop: Mossie Lawlor