Edinburgh had previously confirmed that Viliame Mata and Damien Hoyland faced lay-offs with knee injuries.
Savala, 21, comes in at stand-off for only his second start for the club after Kinghorn was ruled out with a head injury, while Jaco van der Walt makes a timely return from injury to be named among the replacements.
It is a chance for the young playmaker to showcase his talents against one of the toughest defences in Europe.
There can be not doubt that Saracens is a tough place to be thrown in for a young player to be making only their fifth appearance, however he will be able to lean on the experience of other game managers in the side, with James Lang and Mark Bennett making up the midfield, and Argentina international Emiliano Boffelli starting at full-back.
Bennett, Pierre Schoeman, Stuart McInally, WP Nel and Marshall Sykes all return to the starting line-up.
Boffelli – who has two tries in two appearances for the capital side – is in a back three along with Jack Blain and fellow Argentine international Moyano, who are selected on opposite wings.
Bennett returns at outside-centre to partner Lang in midfield, while Savala and scrum-half Ben Vellacott combine at half-back.
An experienced front-row selection sees hooker McInally pack down alongside W P Nel and Schoeman, as lock Marshall Sykes is promoted from the bench to partner Grant Gilchrist in the second-row.
Van der Walt returns from injury to be named among the replacements, while centre Cammy Hutchison makes the 23 after penning a contract extension earlier this week.
Head coach Mike Blair said: "This is a real challenge for the club. Saracens are one of the best teams in Europe and it will give us a really good measure of where we're at.
"We've been really pleased with some of things we've been able to achieve in the URC so far, but this week has a different feel to it and we're just looking forward to the challenge."
Edinburgh have enjoyed a good record in the EPCR Challenge Cup in recent years, making one Final, one Semi-final and two Quarter-Finals since 2015.
The Capital side side will be hoping to go one better than the 2014/15 campaign, which saw the capital club reach the final before falling short against Gloucester.
Blair added: “We talked at the start of the season about the history of the club in both European competitions.
“We reached the Final of the Challenge Cup in 2015 and our guys love the variety of facing different opposition.”
Both Edinburgh and Saracens have enjoyed productive starts to their respective league campaigns and Saturday’s fixture will see two teams in red hot form going head-to-head.
Edinburgh sit second in the United Rugby Championship after seven rounds and have only suffered one defeat.
Similarly, Saracens are up in second of the English Premiership, having won six, drawn one, and lost twice.