The versatile back, who impressed at stand-off in the win over Scarlets last weekend, is injured and is replaced by Jaco van der Walt.
It is one six changes to the starting XV for the match at Stadio Comunale di Monigo.
James Lang, who signed in the summer from Harlequins, will make his first competitive start for Edinburgh. The Scotland centre, who impressed off the bench against Scarlets, comes in for Cammy Hutchison at 12, with the latter dropping out of the squad.
The remaining changes are in the pack. Props Boan Venter and WP Nel rotate into the front-row, with last week’s starters, Pierre Schoeman and Lee-Roy Atalifo, on the bench.
Jamie Hodgson comes in for Marshall Sykes in the second-row, while flanker Connor Boyle makes his second start for his hometown club, replacing Luke Crosbie who moves to the bench.
Edinburgh coach Mike Blair, said: “Benetton are a really strong side. They’ve won the Rainbow Cup and six of their last seven games, including Saturday’s URC opener against a strong Stormers team. They’ll be very confident going into the game.”
Centre Chris Dean and summer signings Ramiro Moyano and Pierce Phillips are all named among the replacements, with Dean in line to make his first appearance of the season, and Moyano and Phillips set to make their competitive debuts for the club.
Edinburgh Rugby (v Benetton, United Rugby Championship, Stadio Comunale di Monigo,
Saturday, 1pm UK time)
15. Henry Immelman
14. Darcy Graham
13. Mark Bennett
12. James Lang
11. Jack Blain
10. Jaco van der Walt
9. Ben Vellacott
1. Boan Venter
2. Stuart McInally
3. WP Nel
4. Jamie Hodgson
5. Grant Gilchrist (c)
6. Jamie Ritchie
7. Connor Boyle
8. Viliame Mata
Subs: 16. Dave Cherry, 17. Pierre Schoeman, 18. Lee-Roy Atalifo, 19. Pierce Phillips, 20. Luke Crosbie, 21. Charlie Shiel, 22. Chris Dean, 23. Ramiro Moyano.