In the backs, Jonny Shiels, Cillian Willis and Clinton Schifcofske all return to the squad.
Not available for selection are the injured trio of Bryn Cunningham, Ryan Caldwell and David Pollock.
Full-back Cunningham suffered a hyper-extension to his right elbow in the Dragons game and a scan will give further details on the injury.
Second row Caldwell also had to be replaced during Ulster's league opener, after suffering a trauma to his right ankle.
Flanker Pollock, the former Ireland Under-20 Grand Slam-winning captain, is continuing his recovery from a hip operation.
For Brian McLaughlin's second competitive match in charge, the Ireland trio of Stephen Ferris, Paddy Wallace and Andrew Trimble are not available for selection under the Rugby Word Cup 2011 player management programme.
The Ulster team and replacements will be confirmed on Friday afternoon.
ULSTER Squad (v Ospreys): Backs (11) - Timoci Nagusa, Darren Cave, Niall O'Connor, Simon Danielli, Ian Whitten, Paul Marshall, Isaac Boss, Ian Humphreys, Jonny Shiels, Cillian Willis, Clinton Schifcofske.
Forwards (12) - Nigel Brady, BJ Botha, Bryan Young, Ed O'Donoghue, Andy Kyriacou, Dan Tuohy, Robbie Diack, Chris Henry, Willie Faloon, Thomas Anderson, Tamaiti Horua, Declan Fitzpatrick.