Wing Scully has been with the USA squad for the last two weeks, while prop Ayerza returns to club duty after playing in the autumn series with Argentina.
Ayerza joins England and Lions duo Tom Youngs and Dan Cole in the Leicester front row, while Thomas Waldrom starts in the No8 shirt.
Adam Thompstone joins Dan Bowden at centre after Matt Smith’s injury in the win over London Irish last weekend.
Nineteen-year-old centre Javiah Pohe, who made his senior debut during this season’s LV= Cup, is among the replacements.
Richard Cockerill, Tigers director of rugby, said: “We battled through the game against London Irish last week to take the points, though we can play a lot better.
“We needed that win after a couple of disappointing results but the squad will be better for it and we know we need to push on from there.”
Friday’s match is shown live on BT Sport, kick-off is at 7.45pm.
Leicester Tigers (v Gloucester, Kingsholm, Friday 7.45pm)
15 Scott Hamilton
14 Blaine Scully
13 Adam Thompstone
12 Dan Bowden
11 Miles Benjamin
10 Toby Flood (c)
9 Ben Youngs
1 Marcos Ayerza
2 Tom Youngs
3 Dan Cole
4 Louis Deacon
5 Graham Kitchener
6 Jamie Gibson
7 Julian Salvi
8 Thomas Waldrom
Replacements
16 Neil Briggs
17 Boris Stankovich
18 Fraser Balmain
19 Sebastian De Chaves
20 Jordan Crane
21 Sam Harrison
22 Owen Williams
23 Javiah Pohe
Gloucester Rugby: 15 Rob Cook, 14 Shane Monahan, 13 Henry Trinder, 12 Billy Twelvetrees, 11 Jonny May, 10 Freddie Burns, 9 Dan Robson; 1 Nick Wood, 2 Darren Dawidiuk, 3 Shaun Knight, 4 Lua Lokotui, 5 James Hudson, 6 Tom Savage (c), 7 Matt Kvesic, 8 Ben Morgan.
Replacements: 16 Huia Edmonds, 17 Yann Thomas, 18 Rupert Harden, 19 Elliott Stooke, 20 Matt Cox, 21 Jimmy Cowan, 22 Mike Tindall, 23 Martyn Thomas.
