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.
Cardiff Blues launch the new Guinness PRO12 season next Sunday when we entertain Zebre Rugby at BT Sport Cardiff Arms Park - and to celebrate the big kick-off we are offering a special ticket offer with Kids for a Quid for this fixture!
Cardiff Blues Rugby Camps will be back next month giving children right across our region the opportunity to participate in rugby during the holidays - and you can book NOW to avoid any disappointment!
Rugby World Cup 2015 continues to grip the nation with over half a million local and international fans enjoying the Official Fanzones up and down the country to watch live matches and enjoy the excitement of the Tournament.
Can't get tickets for the Rugby World Cup? Well now you won't have to miss a second of the action alongside passionate fans as we are running two special events so you can watch the big games with Cardiff Blues and in the company of some Welsh rugby legends!
Prop Sam Hobbs scored a dramatic injury time try - for the second successive season in Galway - as battling Cardiff Blues deservedly took home two bonus points from a pulsating Guinness PRO12 fixture with Connacht at The Sportsground.
New-look Cardiff Blues and Newport Gwent Dragons served up an entertaining pre-season encounter as the visitors edged to victory as the countdown to the new Guinness PRO12 season continued at BT Sport Cardiff Arms Park.