Harlequins' Heineken Cup hopes are hanging by a thread but head coach John Kingston has not given up on securing quarter-final status.

Quins, whose European campaign last season was scarred by the 'Bloodgate' fake injury scandal, have collected just one point from two games in Pool Five.

Their second successive defeat - a 23-19 home loss to three-time European champions Toulouse - means progress from the group stages looks unlikely.

Kingston said: "There is no question our situation in the Heineken Cup now is very difficult.

"But if we can do the business home and away to Sale (in December) and beat Cardiff Blues at home, then who can tell what will happen with the other results."

Quins led 14-0 at half-time, but despite England and Lions wing Ugo Monye's try double, Toulouse recovered as touchdowns from Yves Donguy and Shaun Sowerby underpinned a priceless away win.

"Nobody would have complained if Harlequins had won that game," added Kingston.

"But there is a very, very narrow line between success and failure at this level.

"That was far and away the finest rugby we've played this season, so we are frustrated.

"You can go away and analyse things, but if you drop a high ball, then you fail to spot a three-on-one overlap, then a player trips over as he is heading for the line, you don't need to do much analysing."

While Quins took Toulouse to the wire, Gloucester suffered their heaviest Heineken Cup away defeat against French opposition as Biarritz blitzed them 42-15 at Parc des Sports Aguilera.

Although Gloucester are not out of Pool Two contention, the west country club now cannot afford another defeat, and they still have to visit Glasgow and Newport Gwent Dragons.

"Ultimately, we shot ourselves in the foot by making so many basic errors," lamented Gloucester head coach Bryan Redpath, whose team were destroyed by Biarritz hat-trick star Takudzwa Ngwenya.

"Three of their tries came from two missed tackles and one dropped pass. You just can't compete against a team of the calibre of Biarritz when you give away soft tries like that.

"We were suitably punished, and we have to accept that we weren't good enough."

London Irish's hard work in beating Heineken Cup holders Leinster away from home nine days ago unravelled through a shock 27-25 home defeat against the Scarlets.

Lions fly-half Stephen Jones kicked 17 points to leave the Scarlets in control of Pool Six, and Irish boss Toby Booth admitted: "We were taught a lesson in certain areas of the pitch.

"That game contained more mistakes by us than in eight months last season.

"Take nothing away from the Scarlets - they were good for their victory in the end - but we are disappointed because what was a winnable game slipped through our fingers."

Scarlets chief Nigel Davies turned on his team's critics, claiming: "The fact we've been written off has been a motivating factor for us.

"When I've looked at some of the (television) programmes and what has been written in the media, I've seen that we have barely been mentioned."

Leicester maintained promising momentum in Pool Three, beating Italian hosts Viadana 46-11 and securing a bonus point following a seven-try display that included three for full-back Scott Hamilton.

"It was frustrating and disjointed at times, but we took our tries really well," said Tigers head coach Richard Cockerill.

"We have found from experience in Italy that you have to be patient, go through the phases and take your opportunities.

"Seven tries is probably a decent return in the end. We've scored 11 tries in the last two weeks (of the Heineken Cup), and that is a good return."

Munster, the 2006 and 2008 European champions, recovered from trailing 10-0 at home to Italian side Treviso in Pool One, scoring 41 unanswered points.

South African World Cup winner Jean de Villiers scored one of Munster's seven tries, while their fellow Irish challengers Leinster claimed an impressive 36-13 success in Brive.

Edinburgh, meanwhile, recovered from their mauling by Stade Francais last weekend to edge out Pool Four visitors Ulster 17-13, helped by four Phil Godman penalties.

And in the Amlin Challenge Cup, Wasps overwhelmed Roma 57-0 - forwards Dan Ward-Smith and Dan Leo each claimed try doubles - and there were also two tries each for Miles Benjamin and Alex Grove in Worcester's 38-5 away victory over Olympus Madrid.