New Zealand-born Anscombe has switched mostly between flyhalf and fullback in his previous 18 tests but now has a chance to push for World Cup consideration in the number 10 jersey less than a year out from the tournament in Japan.
His Cardiff Blues teammate Jarrod Evans has been selected on the bench and could earn a first cap, adding to Gatland’s options at flyhalf.
"The new boys introduced themselves last week. Jarrod got up and said it was time he was here seeing as he has been playing above Gareth Anscombe for the last two years. It is great to have that," Gatland told reporters on Thursday.
"There is great competition at the Blues. We have been pleased with Gareth over the last 12 months, his leadership and maturity. Hopefully he makes the most of his opportunity and Jarrod gets a chance as well."
Gatland praised Anscombe for the way he has adapted to the flyhalf role, having predominantly been a fullback while playing in Super Rugby for the Auckland Blues and Waikato Chiefs in New Zealand.
"He made a big decision to leave New Zealand rugby and came over here as a very young 10. He was finding his feet in that position," Gatland said.
"He admits it was a challenge at the start and I think he has really matured in the last 12 months; he was outstanding in Argentina (in June) in a leadership role."
Gatland was facing reporters for the first time since returning from New Zealand after the death of his father.
"A big thank you for all of the messages of support," he said. "I have had hundreds of messages, and myself and my family really appreciate it."
(Reporting by Nick Said; Editing by David Goodman)
