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' 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.