He said, "Nicky is a very accomplished number 10 and can also play at full-back so he offers various options for us. He's trained with us this week and we have added him to the squad."
The Blue & Blacks also give a debut to James Loxton in the number 15 shirt at Eugene Cross Park as they endeavour to kick-start their Principality Premiership campaign after the disappointing home defeat at the hands of Swansea.
Other changes in the starting line-up from last week see the return of Gareth Chapman for the injured Shaun James at centre and the inclusion of Ashley Sweet and Dan Godfrey in the pack where Adam Powell switches from number 8 to flanker.
Cardiff: James Loxton; Ryan Howells, Gareth Chapman, Darren Ryan, Matthew John; Gareth Davies, Tom Slater; Ian George, Rhys James, Phil Osborne, Ashley Sweet, James Down, Adam Powell, Dan Godfrey, Rhys Shellard (captain)
Replacements: Garry Horrigan, Daniel Preece, Dan Partridge, Jake Thomas, Garyn Lucas, Nicky Roberts, Richard Jones