Substitute Sam Davies delivered a commanding performance as the Ospreys fought back superbly to floor French heavyweights Clermont Auvergne in stunning fashion at the Liberty Stadium.
Ospreys saw off a second-half comeback from Newport Gwent Dragons to clinch a hard-fought 12-7 Guinness PRO12 win and make it two Welsh derby victories out of two in the space of six days.
The Ospreys claimed their 12th win in 15 games over the Scarlets, winning an entertaining Guinness PRO12 derby 27-26 in Llanelli – re-vitalising their play-off hopes.
Ospreys' second-half comeback proved in vain but they still collected two losing bonus points in a 33-27 defeat at Bordeaux-Begles to keep their hopes of qualifying for the European Champions Cup quarter-finals alive.
Dan Biggar scored all 19 points to keep Ospreys joint top of Pool Two in the European Champions Cup, but it was an unconvincing performance from the hosts.
After just two rounds of European rugby this season, including some teams having only played a solitary game, the prognosis is already dire for the Guinness PRO12 sides.
Dan Biggar led Ospreys to a 25-13 win over Exeter at the Liberty Stadium as the Chiefs became the first English side to register a defeat in this season's European Champions Cup.
Wales and Ospreys scrum-half Rhys Webb, already ruled out of contention for this year’s World Cup faces an uphill fight to play again at all this season.
Replacement CJ Stander was the hero as Munster stole a 20-18 Guinness PRO12 victory in the final minute to leave Ospreys winless from their opening two matches.
George North scored four tries as Northampton beat the Ospreys in Pool Five while Glasgow held on to beat Montpellier in Pool Four of the European Champions Cup.