Ben Lewis, Craig Mitchell, Hook and Chris Tossell all crossed for the Ospreys before Hook, who added two conversions, dropped a goal to win the game in the final seconds.
In the other game, the Blues defeated the Dragons 34-29, but not before the Dragons threatened to claim an unlikely victory away from home. The Blues led 24-14 at the interval thanks to tries from Gary Williams, Tom Dickens and Jame Roberts, but the Dragons struck back in the second half to almost snatch victory.
A converted penalty try and a try from Jack Liddiate kept them in the hunt in the first half, whilst tries from Alex Walker and Gavin Ferguson helped them into the lead with 20 minutes remaining. Sam Mills added three conversions and dropped a goal before a Rhys Bloomberg try and conversion and penalty from Dai Flanagan won the day.
