Sweeney crosses for try against former club Boxing Day 2008
Huw Evans PA
Dragons Coach Paul Turner confirms fly half Jason Tovey and lock Luke Charteris fail late fitness tests, but centre Ashley Smith returns.
Joe Bearman, Grant Webb, Aled Brew, Pat Palmer and Matthew Watkins are also out. Those injured Dragons players join lock Adam Jones and flanker Dan Lydiate - who are out for the season - plus Danny Lee on the sidelines.
James Arlidge starts at outside-half as Tovey has failed to recover from a knock sustained in last weekend's win over Edinburgh. Bearman is replaced in the back-row by Newport RFC captain Andrew Coombs.
"I'm really hoping it's going to be a high energy game with a lot of movement of the ball and two teams trying to take each other on," said Dragons backs coach Darren Edwards.
"They've got quality players that we will have to stop and to do that, we will have to be in their faces. We are developing a style of play and it is attack."
Newport Gwent Dragons: Martyn Thomas; Will Harries, Tom Riley, Ashley Smith, Richard Fussell; James Arlidge, Wayne Evans; Hugh Gustafson, Tom Willis (capt), Ben Castle, Rob Sidoli, Hoani MacDonald, Andrew Coombs, Gavin Thomas, Toby Faletau.
Replacements: Lloyd Burns, Nigel Hall, Lewis Evans, James Harris, Rhodri Gomer Davies, Adam Hughes, Alex Walker.
Warren Gatland has confirmed he will be joining the fast approaching 50,000-strong crowd at Judgement Day III on Saturday to run the rule over potential Wales Rugby World Cup squad members in the competitive surrounds of the Millennium Stadium.
Cardiff Blues are hosting a special Open Evening this Wednesday night at BT Sport Cardiff Arms Park to give prospective students and parents the chance to discover more about our new and exciting rugby education programme.
Our Cardiff Blues Rugby Camps return this Easter to give children right across our region the opportunity to participate in rugby during the holidays - and after selling out our last two camps you can book NOW to avoid any disappointment!
The players at Cardiff Blues will be hoping to play with some true Gallic flair for the rest of the Guinness PRO12 season - after the region teamed up with a successful French bistrot in the Welsh capital.
Cardiff Blues will be celebrating St David's Day when the region faces Edinburgh Rugby at BT Sport Cardiff Arms Park on Sunday afternoon (kick-off 12.45pm) - with hundreds of children invited as part of our Regional Schools Day.
Fine footwear retailer The Brogue Trader - one of the official sponsors of Cardiff Blues - is celebrating after being recognised by the British Footwear Association at its annual Footwear Industry Awards.
Battling Cardiff Blues produced a second half performance packed full of character and spirit to push Ulster Rugby all the way in an absorbing Guinness PRO12 encounter at a packed out Kingspan Stadium.