A late Morgan Allen try gave the Ospreys a winning 2012-13 LV= Cup start over Gloucester.
Gloucester dominated first-half play with a try from Yann Thomas complementing Billy Burns' kicking.
But Matthew Morgan dropped two first-half goals and kicked three penalties to give the hosts the edge.
Dan Murphy went over for Gloucester, who were also awarded a penalty try. But Tom Grabham went over for the hosts before Allen sealed the win.
Sam Davies, who replaced Morgan in the 59th minute, also kicked a conversion and penalty as he helped the Ospreys see off the Gloucester side coached by his father Nigel.
Ospreys: Ross Jones; Tom Grabham, Ben John, Jonathan Spratt, Will Price; Matthew Morgan, Rhys Webb; Marc Thomas, Matthew Dwyer, Joe Rees, Lloyd Peers, James King, George Stowers, Sam Lewis (capt), Morgan Allen.
Replacements: Nathan Edwards for Grabham (70), Sam Davies for Morgan (62), Tom Haberfield for Webb (62), Rhodri Hughes for Peers (72), Nicky Thomas for Rees (67).
Not Used: Otten, N. Smith, Ellis.
Sin bin: King (26).
Gloucester: Martyn Thomas; Shane Monahan, Drew Locke, Tim Molenaar, Ian Clark; Tim Taylor, Dan Robson; Yann Thomas, Tommaso d'Apice, Dario Chistolini, Elliott Stooke, Will Graulich, Ross Moriarty, Matt Cox, Peter Buxton (capt).
Replacements: Dave Lewis for B Burns (55), Tom Heard for Chistolini (70), Koree Britton for D'Apice (59), Dan Murphy for Y Thomas (46).
Not Used: King, Sparks, Boulton, Reynolds.
Sin bin: Buxton (58).
Ref: David Rose (RFU).