Vicky Irwin will make her Ireland debut in Saturday's TikTok Women’s Six Nations match against Scotland (8pm).
The Sale Sharks player will line out at full-back with Molly Scuffil-McCabe, who made her own debut last weekend in that position, moving to the wing in place of the injured Eimear Considine.
As expected, out-half Nicole Cronin was also ruled out through injury with Nikki Caughey coming in for her first appearance of the championship.
The midfield pairing remains unchanged as Sene Naoupu and Enya Breen start at outside and inside centre respectively, while Ulster's Kathryn Dane partners Railway Union out-half Caughey in the half-backs.
A third change to the side beaten 69-0 by England sees the return of Sam Monaghan, who has recovered from a calf injury, to the second row.
Linda Djougang, Neve Jones and Christy Haney pack down in the front row, with captain Nichola Fryday reunited with Monaghan.
Dorothy Wall, Edel McMahon and Hannah O'Connor are the back row.
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"A couple of injuries have forced us to make minor changes this week, but overall we are very pleased with the dynamic of the team and we're excited to get to work on Saturday," McWilliams said.
"It will be a special moment for us all to have a big home crowd behind us at Kingspan Stadium, but for Neve, Kathryn and Vicky it will be particularly special to play in Belfast.
"We have received huge support in Dublin and Cork so far in this Six Nations and it’s a massive boost for the whole group to have so many people – young and old – behind us as we embark on our journey together.
"We have learned a lot about ourselves over the last six weeks and we hope to produce a strong performance to finish the Six Nations the way we want this Saturday."
Ireland: Vicky Irwin; Aoife Doyle, Sene Naoupu, Enya Breen, Molly Scuffil-McCabe; Nikki Caughey, Kathryn Dane; Linda Djougang, Neve Jones, Christy Haney; Nichola Fryday (capt, Sam Monaghan; Dorothy Wall, Edel McMahon, Hannah O'Connor.
Replacements: Emma Hooban, Chloe Pearse, Katie O'Dwyer, Aoife McDermott, Grace Moore, Maeve Og O’Leary, Ailsa Hughes, Michelle Claffey.
Follow Stormers v Leinster (Saturday 5.15pm), and Ireland v Scotland (Saturday 8pm) via our live blogs on rte.ie/sport and on the RTÉ News App, and watch live on RTÉ2 and RTÉ Player.
Listen to Ireland v Scotland in the TikTok Women's Six Nations on RTÉ Radio 1 and RTÉ Radio 1 Extra.