A great come back by Castletroy in the second half saw the Limerick side come from 10-3 down at half time to snatch victory with a last minute penalty.
Rockwell dominated the opening half despite going 3-0 behind after twelve minutes with a penalty from JJ McDonald.
A try by David Johnson which Coleman Kennedy converted put Rockwell ahead after twenty five minutes and in first half injury time Kennedy added a penalty for Rockwell.
Conor Burns brought Castletroy back into the game with a try on fifty five minutes.
Referee Derek Noonan had to retire injured and was replaced by one of his touch judges.
Entering the final stages McDonald converted a penalty for Castletroy to book them a quarter final tie against the losers of the Ard Scoil Ris v St. Munchin's tie.
Rockwell will now face Crescent College Comp. in the last eight.
Scorers Castletroy College: C Burns try, JJ McDonald 2 pens.
Rockwell College: David Johnson try, Conor Kennedy con, pen.
Castletroy College: Cillian Carroll; David Grant, Eoghan Clancy, Conor Burns, Pat O'Kane; JJ McDonald, Cillian Enright; Aaron Cusack; Ben Burns, Stephen Shinnors; Raymond Burke, Patrick Birmingham; Ian McNamara, Darragh Kennedy, Conor Bonfil.
Rockwell: Coleman Kennedy; Liam Murchan, Sean O'Donoghue, David Johnson, Ronan Maher; Philip Quirke, Aidan Barron; Cillian Farrell, Michael Fitzgerald, Daniel Lanigan-Ryan; Darragh Foley, Aidan Butler; James Feehan, Sonny Dwyer capt, James Counihan.
Referee: Derek Noonan (M.A.R.)
Crescent College Comp. 15, P.B.C. 10.
Crescent College Comp were deserving winners of this tie against the holders P.B.C. at Dooradoyle.
In an evenly contested first half which saw both sides putting in the tackles when it mattered Crescent led 3-0 at half time with a penalty by Dermot Dee after three minutes.
Tommy Duggan levelled for Pres' with a penalty four minutes into the second half but Crescent than hit a purple patch shortly after.
A well constructed try on fifty minutes saw David Culhane touch down and Greg O'Shea converted. A great maul up field by the Crescent pack finished with Greg Barry touching down in the corner for a 15-3 lead.
A late rally by Pres' saw a chip ahead by Duggan being gathered by Gavin O'Callaghan who touched down and Duggan converted.
Scorers Crescent College Comp: David Culhane, Greg Barry tries, Dermot Dee pen, Greg O'Shea con.
P.B.C.: Gavin O'Callaghan try, Tommy Duggan pen, con.
Crescent Comp College: G O'Shea; J Frawley, D Culhane, G Barry, M Mulvihill, C Monaghan, G Fitzgerald; S McGee, A Green, S Gleeson; S McGee, A Green, S Gleeson; C Blake E Casserly; J Sheehan, D Dee, J Dineen.
P.B.C.: Paddy Hegarty; James Daly, Gavin O'Callaghan, Peter O'Brien, Ian Long; Tommy Duggan, Edmund Healy; Gavin O'Herlihy, Max Abbot, Ryan Calnan; Conor Casey, Aidan Lynch; Matthew Curtin (capt), Michael Murphy, Dylan Lane.
Referee: George Clancy (M.A.R.)
Glenstal Abbey 10, C.B.C. 22.
Christians were made work hard for this victory over Glenstal at Clanwilliam Park and only a last minute try by Adam Finn made certain of victory for the Cork side.
Kevin O'Keeffe put Glenstal into the lead with a try and conversion. Number eight for Christians Patrick Leahy scored a try and Ryan Foley converted. A penalty by O'Keeffe put Glenstal 10-7 ahead at the half time whistle.
Foley levelled the scores with a penalty and the scrum half put his side ahead with a try.
Christians had to wait until the final minute to be certain of victory when a great run up the wing by Adam Finn saw him touch down and Foley converted.
Christians will now face arch rivals P.B.C in the quarter finals in three weeks time, while Glenstal will face the winners of Ard Scoil Ris or St. Munchin's.
Scorers Glenstal Abbey: Kevin O'Keeffe try, con, pen.
C.B.C.: Ryan Foley try, 2 cons, pen, Patrick Leahy & Adam Finn tries.
Glenstal Abbey: Paddy Glavey; Eoin Hurley, Andrew Boland (capt), Conor Hughes, Ed Timmons; Kevin O'Keeffe, Cormac McDonagh; James Lane, Jack Boland, Dermot Dolan; Conor Buckley, Richie O'Hara; Kevin Hastings, Rossa Dooley, Tom Ryan.
C.B.C.: Cillian Monaghan; Adam Finn, Jack Whooley, Joe Dowling, Adam McCarthy; Sean Quill, Ryan Foley; Jack Corbett, Charlie Slowey (capt), Rory Burke; Darragh O'Brien, Darragh Moloney; Tadhg Arigan, Ronan O'Sullivan, Patrick Leahy.
Referee: T O'Donoghue (M.A.R.)
Avonmore Milk Munster Schools Junior Cup:Castletroy College 11,Rockwell College 10;
Crescent College Comp. 15,P.B.C. 10;
Glenstal Abbey 10,C.B.C. 22;