Qualification for the quarter-finals from Pool 1 remains very much in the balance after Biarritz Olympique produced a brilliant comeback to beat Worcester Warriors on Thursday night.
The pool looked to be swinging well and truly back in Sales Sharks' favour when Biarritz trailed 25-15 and were down to 14 men following Thomas Synaeghel's.red card at the Parc des Sports Aguilérabut a brace of late tries from Teddy Thomas ensured we could go down to the wire to see who make it through next month.
Thomas crossed for the second time with just seven minutes left in the Basques country to give his side maximum points just a week after they had rescued victory at Sixways with an 80th-minute score from flanker Tanguy Molcard.
The win saw the 2012 Amlin Challenge kings jump to the top of the standings prior to Sale's Friday night clash with Oyonnax but the Sharks responded in fine fashion with a bonus-point success that sees them end the first four rounds of action out in front.
Danny Cipriani was simply outstanding for the 2002 and 2005 tournament winners as he scored two tries and finished with 28 points in the 53-14 victory over a side that had triumphed 16-10 in the reverse fixture at the Stade Charles Mathon.
Their lead over Biarritz is just a single point, though, and they still have to travel to France in Round 6 for what could be a winner-takes-all scenario. It all makes for a hugely exciting instalment of action in Round 5 on the weekend of January 9/10/11/12 when Sale welcome Worcester to the AJ Bell Stadium and Biarritz make the journey to Oyonnax.
A Biarritz win over their domestic rivals would make them favourites for the last eight but accomplishing that mission will be no mean feat given that Oyonnax have already beaten them there in the Top 14 and have also seen off Heineken Cup holders RC Toulon, runners up ASM Clermont Auvergne, French Champions Castres Olympique, Perpignan and Sale in front of their own fans.
Bath Rugby are on the brink of the last eight after they picked up maximum points and Newport Gwent Dragons slipped up in Round 4.
The 2009 Amlin Challenge Cup winners and 1998 Heineken Cup kings need just two points to qualify for the quarter-finals having made it four victories from four with a 63-0 thrashing of Mogliano on Saturday afternoon.
Bath scored nine tries in the away leg in Italy in Round 3 and backed up that 55-8 success with 11 more at The Rec, with Matt Banahan marking his 150th appearance for the club with four touchdowns. Olly Woodburn grabbed a brace, as did Matt Garvey, as Bath recorded their 10th straight win in all competitions.
The West Country side had parted company with director of rugby Gary Gold earlier in the week but they were never in any danger of seeing their European hopes hit hard by a visiting team who are yet to pick up a point in 10 continental fixtures.
The Dragons knew that a win of any sorts over Bordeaux-Begles on French soil on Thursday would set up a thrilling Round 5 clash with Bath in South Wales but they fell short and headed home with their qualification hopes having taken a heavy blow. Lyn Jones saw his team beaten 32-13 at the Stade Andre Moga and they now sit eight points behind Bath and no longer have their fate in their own hands.
Jones had described the first game against Bordeaux as the best yet during his time in charge but Nicolas Sanchez ensured there would be no repeat by kicking 22 points as Raphael Ibanez' troops bounced back with a second win of the European season.
That result saw Bordeaux move to within a point of the Dragons with two games remaining and they could now still be alive in the pool on the final weekend if Bath are beaten at Rodney Parade in Round 5. A bonus point win at home to Mogliano would move Bordeaux to within touching distance of the leaders but they would still have to go England and not only bag maximum points, but also prevent Bath from taking a losing bonus if the English outfit earn a point from their trip to the Dragons.
Even that scenario may not be enough for Bordeaux, though, with the Dragons hoping that a big win over Bath is followed by a French victory at The Rec. Those outcomes could still see the Dragons through given that they travel to Mogliano in Round 6.
The Round 5 clash between Newcastle Falcons and Brive is all set to decide who qualifies for the quarter-finals from Pool 3.
Former Heineken Cup kings Brive lead the way from Newcastle Falcons but it is the English outfit who are in pole position ahead of the final two weekends of action next month.
Both sides have 14 points from their first four games, with Brive having won three and drawn one, while Newcastle have won three and lost one. Brive edged the Round 2 encounter between the pace setters in October but their draw on the road in Italy against Calvisano and their failure to pick up a bonus point in either of their successes against Bucharest Wolves means defeat in Round 5 would likely see their campaign brought to a premature end a week later.
Brive won 20-9 at home to the Romanians on Thursday thanks to a brace of quick-fire tries midway through the second half at the Stade Amédée-Domenech. They trailed 9-3 at the break as Bucharest showed the same sort of toughness that had seen them lead the reverse fixture until the latter stages but converted scores from Victor Lebas and Alfifeleti Mafi meant Brive were suddenly 11 points clear and on their way to top spot ahead of Newcastle's trip to Italy.
The Falcons responded with a hard-fought win for the second week running, with a brace of tries from Zach Kibirige and another from Rory Clegg seeing them home 25-10 at the Peroni Stadium. They were three tries to the good with just under half an hour remaining but were unable to claim a bonus point, although it was always going to be the result against Brive next month that would most likely decide the outcome of the pool.
After the joint leaders meet at Kingston Park on the weekend of January 9/10/11/12, both Brive and Newcastle have home ties in Round 6, with Newcastle hosting Bucharest and Brive facing Calvisano.
London Wasps remain out in front in Pool 4 but their failure to claim a bonus point in Sunday's home win over Grenoble means we are now even more likely to witness a thrilling finish in Round 6.
Wasps have won all four of their pool games so far this season but Bayonne are still right in the mix having picked up maximum points in their last three fixtures following a Round 1 reverse to the English outfit.
Bayonne are now just three points behind the 2004 Amlin Challenge Cup winners ahead of the final two weeks of action next month and they will have home advantage when the two teams clash on the weekend of January 18/19/20. They have the trickier tie in Round 5, though, when they travel to Grenoble, while Wasps host winless Viadana at Adams Park.
Having thrashed Grenoble 47-7 and scored seven tries in France in Round 3, Wasps found life a little tougher in the return fixture in High Wycombe. They were comfortable enough winners thanks to a fine kicking display from Joe Carlisle but they were unable to cross the Grenoble line more than twice and took four points rather than five as a result.
Wasps led 16-0 at the break but Grenoble hit back to narrow the gap to 19-12 before Dai Young's men pulled away once again. James Haskell and Tom Varndell were the Wasps try scorers, with the later grabbing his 33rd try in 39 European games, while Carlisle added 19 points with the boot.
Bayonne had things a lot easier in Italy as they racked up 80 points and touched down 12 times at the Stade Stadio Comunale Pierluigi Zaffanella.
Right wing Martin Bustos Moyano scored a brace of tries and added six conversions, with second row Lisiate Fa'aoso also claiming two scores.
Stade Francais are now heavy favourites to reach the knockout stages after a late Antione Burban try saw them claim a bonus point win over London Irish on Sunday.
The Parisian giants are level with the English outfit at the top of Pool 5 but they crucially top the standings courtesy of a better match points tally in the two games between the pace setters. Irish won the reverse fixture 23-14 at the Madejski Stadium in Round 3 but only picked up four points in the process before Stade took maximum points with a 32-14 success at the Stade Jean Bouin.
Burban crossed three minutes from time to ensure last season's beaten finalists are in pole position for the quarter finals after Jules Plisson, Michael Van Vuuren and Jerome Porical had long since wiped out Andrew Fenby's early score for Irish.
The Exiles had travelled to France unbeaten in Europe this term and with maximum points from their first two fixtures prior to their home win over Stade but it would now be a major surprise if they are still in the running for a first European trophy when the knockout stages commence in April.
Stade host I Cavalieri Prato next time out and then travel to Portugal to face Lusitanos a week later and anything less than back-to-back bonus point wins would be a real shock. Prato ran Stade agonizingly close in Italy in October but only the most pessimistic of French fans would expect a repeat in Round 5.
A maximum point return would guarantee that Stade finish top of the pool, while Irish will have to hope that their rivals fail to gain a bonus point somewhere along the line and that they take advantage at home to Lusitanos and away at Prato.
Elsewhere in the pool at the weekend, Prato made history by achieving a double first in Lisbon. Their 30-19 success at the Estadio Universitario de Lisboa was their maiden away win in the Amlin Challenge Cup and the first time they had achieved back-to-back victories in continental competition.