Davies now faces surgery and at least six months on the sidelines, ruling him out of action for the rest of the season.
Meanwhile Pontypridd's Lewis Jones has been called up to the bench.
"It's unfortunate for Aled to pick up an injury like this," said Evans.
"I certainly wasn't expecting to start, but training has been going well and I just want to take my chance now on Saturday.
"I played against England U18s last year in Swansea. England were very good and came at us quickly in the first ten minutes.
"It was certainly the toughest game I'd played in up until that time and a steep learning curve for me.
"My aim this season was to get into the Under 20 squad so I've achieved that and more by playing for the Dragons already," added Evans.
"I just want to challenge myself now to improve throughout this competition and the rest of the season."