England internationals Steve Borthwick and Richard Wigglesworth and Scotland forward Kelly Brown all come into the side.
Gloucester have also made three changes for the clash - with Freddie Burns, Tim Molenaar and Jim Hamilton handed places in the starting XV.
And with Saracens the favourites after 11 straight wins - including a victory over the Cherry and Whites - coach Bryan Redpath knows his side will have to raise their game once again.
"Sunday is huge for us," he said. "We're aware of that and we've achieved some good things this season. But we want to improve upon the performance down there of three weeks ago.
"We were disappointing that day. Credit to Saracens, they're very efficient and a very workmanlike side. They get some stick but they work hard for each other so we have to fight in every aspect of the game."
Sarries boss McCall said: "Gloucester are a very good side but the result of the game at Vicarage Road last month is irrelevant. We know that we will be facing a very different opponent, but it's a challenge we are looking forward to and we can't wait to get out on the pitch."
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