Paris - Two-time defending champions Toulon have notched up a comprehensive 23-8 victory over Leicester in the European Champions Cup on Saturday while Top 14 rivals Toulouse took a huge step to the quarter-finals with a 12-9 win at Glasgow.
There was a sigh of relief for one of Ireland's trio of former winners as Leinster edged Harlequins 14-13 in Pool 2, the three-time former champions overturning a 24-18 loss to the London side last weekend.
2006 and 2008 champions Munster travel to French giants Clermont on Sunday, with Ulster at Llanelli to play the Scarlets, two must-win games for the Irish provinces.
Back in southern France, Toulon, without Italian prop Martin Castrogiovanni after his expletive tirade aimed at Leicester director of rugby Richard Cockerill over reasons why he had left the English side, scored two tries through Ali Williams and Mathieu Bastareaud.
Welsh full-back Leigh Halfpenny kicked three penalties and two conversions as the Tigers could only respond with a Blaine Scully try and Owen Williams penalty.
Toulon almost got off to the perfect start when Springbok winger Bryan Habana latched on to the kick-off, passed inside to skipper Chris Masoe, whose offload to hooker Guilhem Guirado went too low with the line in sight.
Halfpenny got the scoreboard ticking with a penalty and was on hand to convert an 11th minute try from ex-All Black lock and man-of-the-match Ali Williams with Toulon's power showing in the loose.
Halfpenny nailed two more penalties, but Leicester's Welsh fly-half Owen Williams struggled to find his mark at the posts and also badly miskicking from hand on two occasions.
The visitors finally battled back with a textbook approach and finish, American winger Scully scooting over in the corner after some great work by his forwards, Williams' conversion drifting wide to make it 16-5 at half-time.
Halfpenny missed an early penalty in the second period, but any concerns of a Leicester comeback were put to bed after Bastareaud barged over for a try after fly-half Nicolas Sanchez carved open the defence, the Welsh full-back kicking the extras.
Williams hit his first penalty in the 57th minute, but Toulon closed the doors after that to sit out a comfortable win that leaves them atop Pool 3 on 13 points, with Ulster to play Scarlets later Saturday.
"For me today it's the way we came back from last week," said Ali Williams in reference to the Tigers' 25-21 victory over Toulon at home last week.
Four-time champions Toulouse consolidated their place atop Pool 4 with their hard-fought 12-9 victory over Glasgow.
Sebastien Bezy kicked four penalties, two in each half, to three by Glasgow from fly-half Finn Russell and his replacement Duncan Weir (2).
"It was a very tough game and we were quite lucky because they missed a lot of penalties," said Toulouse flanker Yannick Nyanga.
"It is a long time since we last won the back-to-back games in our pool and we are very happy to have done so. Now we have two big games left to qualify for the quarter-finals."
The result left Toulouse with 16 points from four wins from four games, with Bath now in second, six points adrift, after picking up a bonus point in their 32-12 victory over Montpellier on Friday.
High-profile convert Sam Burgess made his full Bath debut in the win, setting up the first of his team's four tries at their Recreation Ground home, but it was winger Matt Banahan who stole the headlines with a hat-trick.
In Pool 5 Northampton thrashed Italian whipping boys Treviso 67-0 in a bonus-point victory, racking up 11 tries, with Manu Samoa and Ken Pisi both bagging hat-tricks.
Racing-Metro moved into second after a nail-biting 18-14 victory over Ospreys, South African fly-half Johan Goosen kicking a last-minute penalty to calm home worries at the match moved from Paris to Le Mans.
Saracens moved to the top of the tight Pool 1 after a 28-15 home win over Premiership rivals Sale. The winner of the Clermont v Munster game on Sunday will move atop the group.
Collated European Champions Cup results on Saturday, the fourth round of matches (kick-offs SA time):
Saracens (ENG) 28 Sale (ENG) 15
Leinster (IRL) 14 Harlequins (ENG) 13
Toulon (FRA) 23 Leicester (ENG) 8
Glasgow (SCO) 9 Toulouse (FRA) 12
Northampton (ENG) 67 Treviso (ITA) 0
Racing-Metro (FRA) 18 Ospreys (WAL) 14
Clermont (FRA) v Munster (IRL) (17:15)
Wasps (ENG) v Castres (FRA) (15:00)
Scarlets (WAL) v Ulster (IRL) (19:15)
Bath (ENG) 32 Montpellier (FRA) 12