Saracens made it two wins from two in the European Champions Cup as it overcame a spirited Ospreys side 36-34 in a thriller at Allianz Park.

The Premiership leader and defending champion found itself 10 points behind at the half-hour mark as the Welsh side, which was forced into late changes after back injuries to Justin Tipuric and Dan Lydiate, made a roaring start.

Sarries showed their class in the final minutes of the half, though, Schalk Brits's converted try making it 17-17 at the break.

Second-half scores from Liam Williams and Nick Tompkins completed Saracens' comeback, securing a bonus point to top Pool 2 despite a late fightback from Ospreys.

The other game in the group was marred by a sickening injury to Clermont Auvergne's Camille Lopez, the France international fracturing the tibia in his left leg under a tackle from Piers Francis. Clermont expect Lopez to be out for "many months", the five-eighth set to have surgery immediately.

Lopez's injury soured a 24-7 victory for the French side over Northampton Saints, the Premiership outfit also seeing Dylan Hartley yellow carded for catching Rabah Slimani in the face during a ruck.

Benetton Treviso's hopes of a rare European Champions Cup win were ended by a last-gasp Francois Trinh-Duc penalty as Toulon snatched victory 30-29.

The Italian side's last triumph in this competition came in January 2015 but the boot of Ian McKinley had them on the verge of a sensational result against the three-time champion in Pool 5 until Trinh-Duc came to the rescue for the Top 14 heavyweight.

Leicester Tigers bounced back from their opening defeat to Racing 92 with a stunning victory over Castres in Pool 4, scoring seven tries at Welford Road in a 54-29 win.

A sensational opening 40 minutes all-but secured the result as Leicester amassed 35 points to Castres' three, Telusa Veainu scoring a hat-trick as the Premiership side secured a bonus point.

Munster is level with Leicester on six points thanks to a narrow 14-7 success over Racing, the Top 14 side occupying third place just a point adrift after the opening two matches.

Jonathan Sexton put on a kicking masterclass on his return from injury as Leinster dented Glasgow Warriors' hopes qualifying from Pool 3 with a 34-18 win.