The Wales manager watched his team fall to a 1-0 home defeat against Poland on Sunday. Bale played the full 90 minutes in Cardiff but was unable to turn the tide against a resilient Polish outfit. The former Real Madrid star moved to Los Angeles FC in the summer, though he is yet to play a full game for the club.
Jack van Poortvliet and Alex Mitchell join Youngs as the scrum-halves in the 36-man squad.
Sinfield’s previous two challenges have raised more than £5million.