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 face Newport Gwent Dragons in a huge European Rugby Challenge Cup quarter-final on Saturday, April 4 - and you can celebrate pre and post-match with Cardiff Blues and the Cardiff Blues Supporters' Club at BT Sport Cardiff Arms Park!
Welsh Pro Rugby's main sponsor BT Sport will help make it a Welsh derby day to remember for thousands of rugby supporters at the big European quarter-final with the creation of a buzzing Family Village at Rodney Parade.
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!
Supporters are being invited to get on their bike and gear up for an epic charity bike ride from Cardiff to Paris this June - with the last few places now available to raise vital funds for #StayStrongForOws
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.
Argentine ace Joaquin Tuculet scored a sensational try in the eighth minute of injury time as Cardiff Blues produced an astonishing finale to snatch victory over Connacht Rugby after an unbelievable Guinness PRO12 encounter.
A powerful second half surge from new table-toppers Munster Rugby saw the run in three tries and wrap up victory over Cardiff Blues as the Guinness PRO12 season resumed at the newly-developed Irish Independent Park.