The 22-year old was deployed at right-back by Australian national team coach Holger Osieck in Tuesday's drawn friendly with Serbia in Melbourne and performed well according to the German.
Osieck said it was important to test players like Williams in a variety of positions so they can develop in all aspects of the game, essentially improving them as overall players.
"Rhys is an excellent boy. He has a lot to offer. I like him very much and I used him as a right full back," Osiekc said in the wake of the scoreless draw.
"We are not too well-staffed there. If anything should happen to Luke (Wilkshire) there's almost nobody behind.
"Rhys is someone who can play there. But he is so versatile, he can play centre-half, he can play holding midfield. In one of the next games, I may play him there."