Leamy is back at number 8 for what will be only his third appearance of an injury-disrupted season for Munster.
The Tipperary man played in the Thomond Park defeat to the All Blacks and then scored a try against the Scarlets before injurying his knee in that game at Parc y Scarlets.
However, missing from the extended Munster squad announced on Wednesday are Kieran Lewis, Keith Earls, Niall Ronan and Marcus Horan who are all suffering from a stomach bug, as is Tony Buckley.
Ronan O'Gara's hamstring injury, which he sustained against Ulster last Saturday, has not cleared up in time to allow him to participate - but the Munster management remain hopeful that he will be fit in time for the forthcoming Heineken Cup game against Sale Sharks.
The absence of O'Gara, Jeremy Manning, Rua Tipoki and Kieran Lewis means bench duty for Garryowen clubman Conan Doyle and Development player Tom Gleeson, who helped Cork Constitution win the Munster Senior Cup last weekend.
MUNSTER (v Ospreys): Denis Hurley; Doug Howlett, Barry Murphy, Lifeimi Mafi, Ian Dowling; Paul Warwick, Tomas O'Leary; Federico Pucciariello, Jerry Flannery, John Hayes, Donncha O'Callaghan, Paul O'Connell (capt), Alan Quinlan, David Wallace, Denis Leamy.
Replacements: Denis Fogarty, Timmy Ryan, Mick O'Driscoll, John O'Sullivan, Peter Stringer, Conan Doyle, Tom Gleeson.