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.
Thank Blues it's Friday! The weekend will be starting HERE on Friday night as Cardiff Blues tackle Ulster in the Guinness PRO12 at BT Sport Cardiff Arms Park - and we want you to be our guest at our big match day party!
Let the Games Begin! Cardiff Blues launch the Guinness PRO12 season on home soil this Sunday afternoon against Glasgow Warriors (kick-off 4pm) - and we are going to make it a double celebration as we also recognise the achievements of Team Wales!
First team aces Cory Allen, Lloyd Williams, Ellis Jenkins and new signing Jarrad Hoeata were all on hand to watch the next generation of stars when Cardiff Blues held a huge Under-8s Tag Rugby tournament at BT Sport Cardiff Arms Park.
Second half tries from Dan Tuohy and Ian Humphreys saw Ulster claim the Friday night points on offer as Cardiff Blues suffered a 26-9 defeat to the impressive Irish province at BT Sport Cardiff Arms Park.
Clinical Glasgow Warriors produced a devastating final 20 minutes to secure the points on Super Sunday and consign battling Cardiff Blues to a 33-12 defeat in the Guinness PRO12 opener at BT Sport Cardiff Arms Park.
Impressive Cardiff Blues pushed English powerhouse side Leicester Tigers all the way with an hugely encouraging performance as final preparations for the new Guinness PRO12 season continued at Welford Road.