Grace has also been working hard on the training field.
Gatland saying it was the ideal time to bring the wing into the squad, with Giles, Tom Rogers, Theo Cabango and Tomi Lewis injured and Josh Adams rested.
“He got his opportunity with a couple of guys being unavailable,” said Gatland.
“So why not take a punt on him? Bring him into the environment and see how he goes.
“He’s fitted in well. He’s quiet and humble about his success in rugby league.
“Hopefully he can transfer that into the union game.”
Gatland says Wales considered playing Grace against the Wallabies but resisted that temptation of “throwing him in at the deep end” during the 2-0 series defeat.
“We felt he needs a bit more time in the environment,” said Gatland.
“He’s been recovering from a horrendous Achilles injury that he then suffered again.
“He’s taken time in terms of his rehab and making sure he’s done everything right, and we’ve been looking after him as well.”
Gatland says there should no pressure or expectations on Grace.
“He’s not played a lot of rugby since coming back from league,” said Gatland.
“He’s sharp and explosive and we’ve got to try and make sure we get the ball in his hands as much as we can.
“We just want him to enjoy it and see what he can do.”
