Blackrock College caused a major surprise when they ended the AIB Cup run of former champions Cork Constitution at Stradbrook.
It was only 'Rock's third win in 15 AIB League and Cup meetings with the Leesiders.
Tries from wing duo Shane Monahan and David Rowan, both converted by Fionn Carr, had the home side leading 14-0 at half-time.
Con cut the gap to four points by the hour mark, with a try from scrum half Duncan Williams and five points from place-kicker Daragh Lyons, but 'Rock held on.
Blackrock College: Tries: Shane Monahan, David Rowan; Cons: Fionn Carr 2
Cork Constitution: Try: Duncan Williams; Con: Daragh Lyons; Pen: Daragh Lyons
AIB Cup holders Garryowen made it safely through to the competition's quarter-finals at a sodden Dooradoyle.
Craig Woods kicked Ballymena into an early lead but Garryowen grabbed a superb try just before half-time when Gerry Hurley's cross-field kick was gathered and touched down by Ciaran O'Boyle.
8-3 in front at the break, the Limerick men pushed on with out-half Alan Kingsley, winger Keith Earls and replacement Anthony Kavanagh all registering tries.
Ballymena consoled themselves with a late try from centre Joel Semple.
Garryowen: Tries: Ciaran O'Boyle, Alan Kingsley, Keith Earls, Anthony Kavanagh; Cons: Conor Kilroy 3; Pens: Conor Kilroy 3
Ballymena: Try: Joel Semple; Pen: Craig Woods
UCC made life difficult for Shannon at the Mardyke before the Limerick giants secured their spot in the AIB Cup's last-eight.
The students fought back from 20-0 to level the game, before tries from number 8 David Quinlan and winger Stephen Kelly saw Shannon home.
Full-back Mossie Lawlor touched down twice during the opening 20 minutes, but a well-taken try from centre Ivan Dineen reduced Shannon's advantage to 20-10 by half-time.
A Scott Deasy penalty and an intercept try from Dineen got UCC level before Shannon's late show.
UCC: Tries: Ivan Dineen 2; Cons: Gavin Dunne, Scott Deasy; Pens: Gavin Dunne, Scott Deasy
Shannon: Tries: Mossie Lawlor 2, David Quinlan, Stephen Kelly; Cons: Andrew Thompson 4; Pens: Andrew Thompson 2
Clontarf accounted for Division Two side De La Salle Palmerston in this well-contested AIB Cup tie at Castle Avenue.
Determined DLSP grabbed tries in either half from back rowers Conor J Power and Niall Smullen.
But 'Tarf, who led 10-8 at the break, had too much in the arsenal. Hooker Niall Carson piled over off lineout drives for two tries in the opening half.
And victory was secured when wide men Phil Howard and Max Rantz-McDonald both crossed the whitewash in the closing quarter.
Clontarf: Tries: Niall Carson 2, Phil Howard, Max Rantz-McDonald; Cons: Ian Keatley 2
De La Salle Palmerston: Tries: Conor J Power, Niall Smullen; Con: Phil de Barra; Pen: Phil de Barra
UL Bohemians crashed out of the AIB Cup at the hands of UCD at Belfield. It was UCD's fifth win in 11 league and cup meetings with Bohs.
An intercept try from centre Andy Cummiskey got them on their way and full-back Conor Quinn scored soon after.
Tries from back rower James O'Neill and winger Ian Hanly cut the gap for Bohs to 22-15 at half-time.
Crucially, UCD scored tries either side of half-time with lock Brian Cawley and winger Cian Aherne both on target.
UCD: Tries: Andy Cummiskey, Conor Quinn, Brian Cawley, Cian Aherne; Cons: Cillian Lett 2; Pen: Cillian Lett
UL Bohemians: Tries: Ian Hanly, James O'Neill, Mike Long; Cons: Fergal Lawlor, Paul Warwick; Pen: Fergal Lawlor
Galwegians are through to the AIB Cup quarter-finals for the third year running after a comfortable win over Old Belvedere at Crowley Park.
After shipping a ninth-minute try to Belvedere flanker Richie Leyden, 'Wegians scored seven unanswered tries to power clear.
Scrum-half Robbie Shaw and front rowers Joey Merrigan and Brian McGovern touched down during the first half.
'Wegians tagged on another 22 points with tries from centre Brett Sweeney, back rowers Liam Casserly and Martin Webdale and hooker Conor Muldoon.
Galwegians: Tries: Robbie Shaw, Joey Merrigan, Brian McGovern, Brett Sweeney, Liam Casserly, Martin Webdale, Conor Muldoon; Con: Peter Durcan
Old Belvedere: Tries: Richie Leyden, Richie Murphy; Pen: Brian Collins
St. Mary's College v Clonakilty and Malone v Bruff were both postponed
The Mayo derby went Westport's way as they beat Castlebar 10-3, while their Connacht neighbours Sligo overcame Coleraine by 20-17. Tullamore easily beat Monivea 37-3, while Clogher Valley accounted for Cooke on a 15-10 score-line.
The game between Kanturk and Crosshaven was postponed