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.
Season Ticket holders at Cardiff Blues are reminded that they gain FREE entry to the British & Irish Cup pool fixtures this season - starting with Saturday's home fixture against Nottingham Rugby at BT Sport Cardiff Arms Park (kick-off 2.30pm).
Teenage Cancer Trust will be collecting for valuable funds at BT Sport Cardiff Arms Park on Saturday afternoon ahead of our British & Irish Cup fixture with Nottingham Rugby (kick-off 2.30pm). Ahead of the game, we take a closer look at the charity and discover how they are making a difference...
Cardiff Blues suffered a first defeat of the season in the European Rugby Challenge Cup as a second half burst of tries from Harlequins saw the English side claim victory at BT Sport Cardiff Arms Park.