Rory Best and Stephen Ferris feature for the first time this season. Under IRFU regulations, they are permitted to each play up to 40 minutes in Thursday's match.
Young prop Paddy McAllister had been named in the squad, despite suffering injuries to his neck and back following a heavy collision in the first friendly against Bath. He will be subject to a medical fitness test later this week but his recovery has been pleasing.
Also included in the extended squad is Adam D'Arcy who is currently on trial with Ulster from the Manly Rugby League side in Australia. Adam, who is 23 and a full-back, linked up with Ulster last week.
Ulster Rugby operations director David Humphreys explained: "We have one full contract left to fill for the 2010/11 season and we're looking at Adam as a potential player for that place.
"Should he get some game-time on Thursday, it will be a huge opportunity for him to show us what he can potentially do for Ulster."
Commenting on his squad selection and the visit of Leeds, head coach Brian McLaughlin said: "The team we put out against Leeds will be fairly close to who we are aiming to select for the home Magners League opener against the Ospreys at Ravenhill in just over a week's time.
"We were very disapointed with the result against Harlequins last weekend but we were happy with areas of the overall performance, particularly our defence and how our younger players performed which is important for progression.
"Against Leeds this Thursday we're looking for both a winning result and a good performance. We need a good performance to take us into the Ospreys match in the Magners League but we're very keen to get a win, not only for ourselves but for the Ravenhill crowd as well."
He added: "It's been a mixed pre-season period to date, frustrating because we've not had all our players available but at the same time that means we've had the opportunity to play some of the younger guys and we've been really impressed by how they've handled themselves.
"Leeds are a Premiership side who will provide us with some really good quality opposition ahead of our first competitive game in the league.
"We need to hold onto the ball, which we found difficult against 'Quins last weekend and have confidence in our game."
ULSTER Squad (v Leeds Carnegie) - Backs (11): Ian Porter, Michael Heaney, Niall O'Connor, Ian Humphreys, Jonny Shiels, Darren Cave, Ian Whitten, Craig Gilroy, Tommy Seymour, David McIlwaine, Adam D'Arcy.
Forwards (14): Bryan Young, Rory Best, Declan Fitzpatrick, Nigel Brady, Paddy McAllister, Adam Macklin, Johann Muller, Tim Barker, Ryan Caldwell, Stephen Ferris, Willie Faloon, Pedrie Wannenburg, Robbie Diack, Thomas Anderson.