Defending champions Leinster lost 28-21 at home to Clermont Auvergne in the Heineken Cup today, their second defeat by the French side leaving their hopes of retaining the trophy hanging in the balance.
Clermont stormed into a 25-9 lead thanks to a Wesley Fofana try and 20 points from Morgan Parra, but Leinster scored late tries through Shane Jennings and Fergus McFadden to claim a bonus point.
Clermont lead Ireland's Leinster, who have won the competition for the last two seasons, by eight points at the top of Pool Five with two matches remaining.
Exeter are one point behind Leinster following a 30-20 win over bottom side Scarlets.
Northampton pulled off a courageous 10-9 win at last season's runners-up Ulster just a week after the Irish side crushed them 25-6 on their own ground.
The English team ended Ulster's 13-match unbeaten run in all competitions, Ruan Pienaar missing a late penalty to condemn the hosts to their first competitive defeat of the season.
Ulster still top Pool Four with 15 points, five ahead of their opponents, who scored the only try of the match through No. eight GJ van Velze.
English champions Harlequins moved to the brink of the quarter-finals after running in seven tries in a 53-5 demolition of Italian team Zebre.
Biarritz beat Connacht 17-0 yesterday to stay in touch with the leaders.
Twice European champions Leicester moved top of Pool Two with a last-gasp 14-13 win at Italy's Treviso and Ospreys pulled off a shock 17-6 victory over previous leaders Toulouse to leave the group wide open.
Racing Metro remain in control of Pool One following a 15-3 win at Edinburgh yesterday.