Munster outplayed four-time champions Toulouse to reach the European Cup semi-finals Saturday but Ulster slumped to a controversial defeat to Saracens after being reduced to 14 men inside four minutes.
Munster, themselves former two-time title holders of the continent's elite club tournament in 2006 and 2008, routed Toulouse 47-23 and will be joined in the last four by Saracens who edged Ulster 17-15.
Clermont clinched a nail-biting 22-16 win over Leicester for their 75th successive home victory.
Munster will play the winners of the Toulon v Leinster quarter-final scheduled for Sunday, while Clermont will travel to Saracens on April 26.
At Ravenhill, Ulster's New Zealand full-back Jared Payne was red-carded after just four minutes for a crunching tackle on Alex Goode while the Saracens man collected the ball in mid-air.
Goode was stretchered off while Payne pleaded that he had been keeping his eye on the ball and had not targeted the player.
Despite being a man down, Ulster took the lead through a Ruan Pienaar penalty.
The South African scrum-half, who was to be replaced eventually when he felt his injured shoulder, then missed the first of two penalties before Saracens' England winger Chris Ashton scored the first of his two tries on 22 minutes.
Owen Farrell missed the conversion before Pienaar put Ulster back in front with two penalties for a 9-5 lead at the interval.
Mouritz Botha scored Saracens' second try eight minutes after the break but Farrell missed the extras.
Saracens' one-man advantage eventually told when Ashton scored his second try of the night in the 67th minute after an accurate cross-field kick from Farrell.
Paddy Jackson popped over two late penalties but Ulster couldn't find the breakthrough despite their epic struggle which saw a 35-phase move thwarted at the death.
Ulster captain Johann Muller insisted Payne should only have been penalised with a yellow card for the tackle on Goode.
- Breathless start -
"He was looking at the ball all the time. He didn't see him coming. It was dangerous and it's not right but it's a yellow card not a red," said Muller.
A breathless start by Munster at Limerick's Thomond Park was rewarded in the fifth minute.
After more than 20 phases in the French 22m area, fly-half Ian Keatley and Simon Zebo moved the ball right to Keith Earls, the winger crossing in the corner for a try Keatley converted.
Former All Black Luke McAlister and Keatley exchanged penalties before the Kiwi bagged two more before Munster prop Dave Kilcoyne scored the home side's second try just minutes into the second half with Keatley kicking the extras.
A dominant Munster forward display again shone through, man-of-the-match CJ Stander, who'd come on for injured captain Peter O'Mahoney, driving over from close range.
Keatley converted and suddenly it was 27-9 after 47 minutes,
Completely against the run of play, Toulouse hit back with a well-finished try by ex-All Black winger Hosea Gear.
Munster responded with a Keatley penalty and a Casey Laulala try after Lionel Beauxis' disastrous attempt at a quick 22m drop-out backfired.
Toulouse's Samoan flanker Joe Tekori powered over for a try converted by Beauxis with 10 minutes remaining.
But any thought of an improbable comeback was quashed when first Zebo crashed over in the corner and then Paul O'Connell scored after the hooter, Keatley having the final word.
"It was one of those days where everything came off for us," Munster lock Paul O'Connell said.
In Clermont, a superior out-of-hand kicking game and dominant forward display saw the home side past former two-time champions Leicester, who were 16-0 down at one point.
France scrum-half Morgan Parra opened the scoring with a 14th minute penalty.
Centre Wesley Fofana scored soon after, Leicester failing to close down Aurelien Rougerie in midfield and Georgian prop David Zirakashvili providing the crucial pass after a delicate offload from Fofana himself.
Parra hit the conversion and two penalties to take Clermont out to 16-0.
Leicester responded brilliantly, Welsh fly-half Owen Williams' crosskick fed to American winger Blaine Scully and offloaded to No 8 Jordan Crane for a try Williams converted.
Parra hit a third penalty on the stroke of half-time, but Williams, preferred in the Tigers' playmaking position to England international Toby Flood, clawed back three penalties to make it 19-16 with 20 minutes to play.
Replacement Leicester flanker Thomas Waldrom was then yellow-carded, Parra booting the penalty and Clermont holding on as the game went to the wire.