Clinton Schifcofske replaces the injured Bryn Cunningham at full-back, while Darren Cave comes in to partner Ian Whitten in the centre.
Ulster's newest signing, Tamaiti Horua, starts his first match on the bench.
Chris Henry will once again captain the Ulster side in Rory Best's injury-enforced absence.
Speaking ahead of Saturday's game, Ulster forwards coach Jeremy Davidson said: "We all know that the Ospreys are a star-studded side and we are looking for a big performance this week.
"You just have to look at the Ospreys squad to see what strength and depth they have. Pick any of the players and they have a strong team, so we know that Liberty Stadium is going to be a big ask.
"In that respect we are hoping to put a lot of things straight after the disappointment of last week.
"All the players have worked their socks off in training and are in the best physical condition they have ever been.
"We will be looking forward to getting our international players back into the team soon, as there is no doubt their return can bring performances up a level."
ULSTER (v Ospreys): Clinton Schifcofske; Timoci Nagusa, Darren Cave, Ian Whitten, Simon Danielli; Ian Humphreys, Isaac Boss; Bryan Young, Andy Kyriacou, BJ Botha, Dan Tuohy, Ed O'Donoghue, Chris Henry (capt), Willie Faloon, Robbie Diack.
Replacements: Nigel Brady, Declan Fitzpatrick, Tamaiti Horua, Thomas Anderson, Cillian Willis, Niall O'Connor, Jonny Shiels.