|Ospreys (13) 22|
|Try: Ardron Con: Biggar Pens: Biggar (5)|
|Dragons (6) 11|
|Try: Rees Pens: Prydie (2)|
Ospreys returned to the top of the Pro12 with victory over Dragons in a disappointing derby match.
A try from back-row Tyler Ardron and five Dan Biggar penalties put Ospreys in front at the Liberty Stadium.
But Dragons replacement Richie Rees's late try reduced the deficit, after Dragons prop Brok Harris and Ospreys hooker Scott Baldwin was sin-binned for infringements at the scrum.
Ospreys held out to move one point above Glasgow at the top of the table.
Dragons full-back Tom Prydie opened the scoring with a penalty, but Ospreys fly-half Biggar levelled with a straightforward kick before Ardon scored on the half-hour mark.
After Wales flanker Dan Lydiate charged through his former side's defence to within a yard of the try line, Biggar floated a long pass to number eight Ardron, who touched down in the corner.
Biggar converted, then traded penalties with Prydie as the hosts went in at half-time with a 13-7 lead.
Wales international Biggar kicked a 40-yard penalty five minutes into the second half and added another after Dragons flanker Lewis Evans went off with a head injury.
Dragons prop Brok Harris and Ospreys replacement hooker Scott Baldwin were sent to the bin in quick succession in the final 20 minutes.
Dragons hit back when Richie Rees dived over after a series of pick-and-drives on Ospreys' line.
But Biggar ended any hope of a comeback with another penalty after Dragons infringed in their own 22.
Ospreys: Dan Evans; Richard Fussell, Ashley Beck, Josh Matavesi, Eli Walker; Dan Biggar, Rhys Webb; Duncan Jones, Sam Parry, Dmitri Arhip, James King, Alun Wyn Jones (capt), Dan Lydiate, Justin Tipuric, Tyler Ardron.
Replacements: Scott Baldwin, Gareth Thomas, Aaron Jarvis, Rynier Bernardo, Sam Lewis, Martin Roberts, Sam Davies, Hanno Dirksen.
Newport Gwent Dragons: Tom Prydie; Matthew Pewtner, Tyler Morgan, Jack Dixon, Hallam Amos; Jason Tovey, Jonathan Evans; Phil Price, Elliot Dee, Brok Harris, Andrew Coombs, Rynard Landman (capt), Lewis Evans, Nic Cudd, Taulupe Faletau.
Replacements: Rhys Buckley, Owen Evans, Lloyd Fairbrother, Matthew Screech, James Thomas, Richie Rees, Dorian Jones, Geraint Rhys Jones.
Referee: Dudley Phillips (IRFU)
Assistant Referees: Nigel Owens, Martyn Lewis (both WRU)
Citing Commissioner: Dennis Jones (WRU)
TMO: Gareth Simmonds (WRU)