Taking his place in the back row is South African Robbie Diack who will start at number 8 having recovered from a recent ankle injury.
Willie Faloon has been selected at openside flanker, with Chris Henry making way. Saturday's match will mark Faloon's first start in this season's Heineken Cup.
Faloon's Ballynahinch club-mate Nevin Spence has retained his starting place in Ulster's midfield after an impressive showing in the 22-18 victory at Ravenhill.
Previewing this weekend's return leg, head coach Brian McLaughlin said: "It's a huge game for us. Last season we beat Bath to get our first win on English soil, but that's history.
"It's another game for us and the importance for us moving forward in this competition is immense.
"We have to go there and get a win. Last season it was smashing to win there and there's no doubt that it gave us great confidence for the rest of the season.
"But this is what it's all about now and we need to make sure we do a job and come away with the points."
Springbok lock Johann Muller, who will captain Ulster once again, said: "In that last 15 minutes (last Saturday), Bath started throwing the ball around a bit and they stretched us in defence.
"There were a couple of tired bodies out there but I expect them to do that from the word go on Saturday.
"If the weather allows it, I think they're going to try and stretch us a bit and play a little bit more rugby. But, at the end of the day, when you play more rugby there's a chance that you can make more mistakes.
"Our defence has got to be right up there again and we have to play a bit better. At some stages we played some great rugby and at others we were quite poor.
"We gave away a lot of soft turnovers and if we can make sure we don't give easy ball away, we'll be right in it."
Conditions in Bath are looking good at present and given the weather conditions, Ulster are making all possible efforts to ensure they make it to Bath for Saturday's game.
With the Belfast airports closed, there are new travel arrangements being made for the management and players who have made the bus journey down to Dublin.
Ulster Rugby would advise all ticket holders travelling from the province to keep in touch with their travel providers.
ULSTER (v Bath): Adam D'Arcy; Andrew Trimble, Nevin Spence, Paddy Wallace, Simon Danielli; Ian Humphreys, Ruan Pienaar; Tom Court, Nigel Brady, BJ Botha, Johann Muller (capt), Dan Tuohy, Pedrie Wannenburg, Willie Faloon, Robbie Diack
Replacements: Andi Kyriacou, Paddy McAllister, Bryan Young, Tim Barker, Chris Henry, Paul Marshall, Ian Whitten, Jamie Smith.