The last eight boasts three Welsh and two Scottish teams, with both Munster and Leinster - who kick off the Irish involvement at Lansdowne Road on Friday, April 29 - confirming home draws against Edinburgh and Glasgow by ironically beating their quarter-final opponents over the league's final weekend.
Ulster travel to meet league champions the Ospreys at St Helen's on Saturday, April 30, courtesy of last Friday's 16-3 defeat of the Scarlets and their eighth place league finish.
Ulster claimed the inaugural Celtic Cup in December 2003, coming from behind to beat Edinburgh 27-21, mainly due to David Humphreys' kicking haul of 17 points.
Munster, meanwhile, have had their tie with Edinburgh confirmed for Saturday, April 30, at either Thomond Park or Musgrave Park.
The winners of that clash will face either Leinster or Glasgow away in the semi-finals over 6/7/8 May, with the Dragons or Scarlets hosting the Ospreys or Ulster in the last four.
Memories of previous Leinster and Munster Celtic clashes will immediately bring 2001's final to mind when 14-man Leinster claimed the inaugural league title - winning 24-20 over the men in red at Lansdowne.
CELTIC CUP 2004/05 Quarter-Finals:
(1) Neath Swansea Ospreys v Ulster (8), St Helen's, Saturday, April 30 (kick-off 5.30pm, live S4C)
(2) Munster v Edinburgh Rugby (7), venue tbc, Saturday, April 30 (kick-off 7.30pm, live Setanta Sports Ireland)
(3) Leinster v Glasgow Rugby (6), Lansdowne Road, Friday, April 29 (kick-off 7.30pm, live Setanta Sports Ireland)
(4) Newport Gwent Dragons v Llanelli Scarlets (5), Rodney Parade, Friday, April 29 (kick-off 7.05pm, live BBC Wales)