O'Halloran and Marmion return to boost hosts
With the Toyota Cheetahs competing at the top of Conference A, the South Africans' ineligibility for Europe means that Connacht are duelling with Cardiff Blues for that final automatic Champions Cup spot, and they trail by one point.
Ulster, meanwhile, need to keep tabs on Scarlets and Leinster in Conference B and will enter this game buoyed by their recent Champions Cup displays.
Fresh from signing a new two-year contract with Connacht, Tiernan O'Halloran returns at full-back. He is joined by Niyi Adeolokun and Matt Healy, who scored four tries in Connacht's win over Brive last weekend. Jack Carty and Kieran Marmion form the half-back pairing after the latter, another to sign on the dotted line with relatively little fanfare of late, was rested.
In the pack, Denis Coulson comes in at loosehead in place of the injured Denis Buckley.
He is joined in the front-row by hooker Shane Delahunt and Finlay Bealham at tighthead.
In the back-row, flanker Jarrad Butler returns from injury.
Ulster centre Darren Cave, who made his first appearance for the province against the Border Reivers in April 2007, will become the sixth Ulster player to breach the 200 cap barrier; he starts at inside centre, where he will be paired with Louis Ludik.
In the back-three, Andrew Trimble returns to the starting XV on the left wing, with Craig Gilroy on the right and Jacob Stockdale shifting to full-back. Peter Nelson is at out-half alongside scrum-half John Cooney.
Europe has provided a welcome relief for Connacht, who have lost their last two Guinness PRO14 matches, but gained maximum league points from their back-to-back European Challenge Cup encounters against Top 14 opponents Brive.
Ulster are unbeaten in their last five matches since their 25-10 reversal at home to Leinster.
Connacht have won just one of their last 11 against Ulster.