That one change sees Denis Hurley return to the matchday squad with Rua Tipoki making way - although Hurley has to content himself with a place on the replacements bench as McGahan pairs the fit-again Barry Murphy with Lifeimi Mafi in midfield.
Paul Warwick starts at number 10, with Ronan O'Gara waiting in the wings.
Up front, Mick O'Driscoll gets in ahead of Paul O'Connell and the Corkman will captain the side. Frankie Sheahan also gets to start on this occasion with Jerry Flannery demoted to a very strong-looking bench.
MUNSTER (v Newport Gwent Dragons): Keith Earls; Doug Howlett, Barry Murphy, Lifeimi Mafi, Ian Dowling; Paul Warwick, Tomas O'Leary; Federico Pucciariello, Frankie Sheahan, Tony Buckley, Donncha O'Callaghan, Mick O'Driscoll (capt), Donnacha Ryan, John O'Sullivan, David Wallace.
Replacements: Marcus Horan, Jerry Flannery, Paul O'Connell, Justin Melck, Peter Stringer, Ronan O'Gara, Denis Hurley.