THE Dragons have suffered a festive blow with influential back row forward Ollie Griffiths out of all three derby clashes, while fly-half Arwel Robson’s injury jinx has struck again.

Griffiths limped off in the European Challenge Cup defeat to Northampton a fortnight ago after having his right leg heavily strapped.

A knee injury means that the Wales hopeful will be out of action for six weeks and miss the chance to impress Warren Gatland in Friday’s clash with Cardiff Blues in the capital, the December 30 encounter with the Ospreys in Newport then trip to the Scarlets.

The 23-year-old from Newbridge has been a talisman for the Rodney Parade region this season with his dynamism both in defence and attack.

The Dragons experimented with captain Cory Hill at blindside rather than his primary position of lock against Clermont Auvergne’s heavy pack last weekend.

He joined Wales internationals Ross Moriarty and Aaron Wainwright in the back row while other options for Friday’s trip to the capital – and an encounter with the Blues’ breakdown specialists on the fast plastic pitch – include Harrison Keddie, Nic Cudd, James Benjamin, Lewis Evans and Huw Taylor.

Robson will not be in the battle for the 10 jersey until the PRO14 run-in at the earliest after suffering a serious hamstring tear in the preparations for Clermont.

The 21-year-old from Ystrad Mynach has endured a frustrating season after a pair of summer ankle operations.

Robson has been limited to just five appearances after he endured another ankle blow in the loss at Glasgow and then strained a hamstring in the team run ahead of the defeat in Northampton when he was set to start at fly-half.

Josh Lewis wore 10 on his back in the European fixtures and Gavin Henson made his return from a knee issue in Clermont, although he didn't come off the bench.

Jason Tovey, who had been playing in the league on permit from Cross Keys, was ineligible for the Challenge Cup.

Blindside Keddie, hooker Richard Hibbard and wing Jared Rosser are expected to be back in contention for Cardiff after concussions but Wales centre Tyler Morgan suffered a blow to the head in France and is going through the return to play protocols.