Ian Humphreys has been preferred at fly-half ahead of Niall O'Connor for Ulster's Magners League clash with Connacht on Friday night.
And Ireland trio Stephen Ferris, Rory Best and Paddy Wallace come into the side after being on international duty.
Winger Mark McCrea will make his first start in place of Andrew Trimble.
Keith Matthews starts for Connacht for the first time since September having overcome a calf injury and is partnered at centre by Mel Deane.
Fionn Carr and Troy Nathan line out on the wings.
Ian Keatley and Frank Murphy return to renew their half-back partnership while up front, hooker Sean Cronin is joined in the front row by Brett Wilkinson and Robbie Morris.
Tim Donnelly is named among the replacements for the first time this season having recovered from a shoulder injury.
Ulster currently lie eighth in the Magners League with Connacht three points behind their Irish provincial rivals in bottom place.
Williams knows the importance of this fixture in terms of league positions.
"We have a lot of respect for Connacht, they are a good side and play a hard game of rugby but we are more determined than ever and we are going out to win.
"We have performed well in winning our last two Magners games and beat a spirited Munster side.
"We will not hide from this Connacht side. The guys are hungry to play and continue on from the form we have shown recently."
Ulster have not lost to Connacht at Ravenhill for 48 years.
Ulster: B Cunningham; T Nagusa, D Cave, P Wallace, M McCrea; I Humphreys; C Willis; J Fitzpatrick, R Best, capt, B Botha, E O'Donoghue, R Caldwell, S Ferris, D Pollock, R Diack.
Replacements: N Brady, T Court, M McCullough, K Dawson, I Boss, P Steinmetz, S Danielli.
Connacht: G Duffy (cpt), F Carr, M Deane, K Matthews, T Nathan, I Keatley, F Murphy; B Wilkinson, S Cronin, R Morris, M McCarthy, A Farley, R Ofisa, J O'Connor, C Rigney.
Replacements: A Flavin, R Loughney, A Browne, M Swift, K Campbell, T Donnelly, J Hearty.
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