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.
Tickets are on sale NOW for our huge opening Guinness Pro 12 fixture of the season against Glasgow Warriors - and we've frozen ticket prices this season so watching top-class rugby at BT Sport Cardiff Arms Park is affordable to all!
In its sixth year the Blues Cup once again showed to be huge hit throughout the region and is a great advert for the community game as each of the six finalists across the three age groups produced rugby of an outstanding level resulting in 14 tries.
Cardiff Blues are going green this season after launching a new European shirt with an environmental pledge - and now sponsors Wessex Garages are making sure the region is on the right road to deliver on our green promise!
Inspired Cardiff Blues enjoyed Judgement Day at the Millennium Stadium as they secured a tense 17-13 win over regional rivals Scarlets in a feisty and enthralling encounter in the RaboDirect PRO12 on Easter Sunday.