Williams takes his place in a star-studded back-row that also includes captain Sergio Parisse and World Cup winning flanker Joe van Niekerk.
Scarlets prop Thomas has been rewarded for an impressive season at club level with a return to the international fold and he takes his place on the loose-head side of the scrum, with Toulon’s Sebastien Bruno and Carl Hayman packing down alongside him.
Cardiff Blues captain Paul Tito keeps his place in the second-row as the invitational side look for their second victory of the summer after beating England at Twickenham last weekend.
15 Isa Nacewa (Leinster and Fiji)
14 Paul Sackey (Toulon and England)
13 Seru Rabeni (La Rochelle and Fiji)
12 Mathieu Bastareaud (Stade Francais Paris and France)
11 Doug Howlett (Munster and New Zealand)
10 Brock James (Clermont Auvergne)
 9 Sebastien Tillous-Borde (Castres Olympique and France)
 1 Iestyn Thomas (Scarlets and Wales)
 2 Sebastien Bruno (Toulon and France)
 3 Carl Hayman (Toulon and New Zealand)
 4 Iosefa Tekori (Castres Olympique and Samoa)
 5 Paul Tito (Cardiff Blues)
 6 Joe van Niekerk (Toulon and South Africa)
 7 Martyn Williams (Cardiff Blues and Wales)
 8 Sergio Parisse (captain, Stade Francais Paris and Italy)
Replacements are:
16 Leonardo Ghiraldini (Benetton Treviso and Italy)
17 Davit Kubriashvili (Toulon and Georgia)
18 Erik Lund (Biarritz Olympique and Norway)
19 George Smith (Toulon and Australia)
20 Lloyd Williams (Cardiff Blues)
21 Willie Mason (Toulon)
22 Benoit Baby (Clermont Auvergne and France)
