Inglis, who retired in April 2019, shocked the rugby league world when he signed a one-year deal with the Wolves for the 2021 Super League season on Tuesday.

The former South Sydney and Melbourne Storm superstar is one of the greatest players of the modern era, playing in 39 Tests for Australia and 32 Origins for Queensland but will be 34 when he debuts for Warrington next March.

Inglis was hampered by shoulder and knee injuries in the final years of his career with the Rabbitohs, who he helped win a premiership in 2014, and also struggled with mental health issues.

Morley left the Roosters after six seasons to join Warrington in 2007 and said he understands why Inglis wants to play again and backed him to be a success at his former club.

"When I retired in 2015 I was ready" Morley told AAP.

"I had played for 20 years and couldn't wait to hang up the boots.

"But after being retired for about a year it was amazing how refreshed I felt.

"You are not doing the day in, day out at training and you are not getting whacked at the weekend.

"I felt I could have easily come back and played. I didn't do it, but the reinvigoration you get from being away makes it very easy to understand why he wants to return.

"He is not coming back from a career-ending injury so it shouldn't be as difficult for him to get his body ready to play top-level rugby league again."

Former St George Illawarra coach Steve Price has assembled a talented squad at Warrington with Gareth Widdop, Blake Austin and former South Sydney prop Jason Clark to be among his new teammates.

"It's a great coup for Warrington, they have a number of star players there and they want to bring over the best and there is no bigger name than Greg Inglis," Morley said.

"There no doubting his ability. When he was in his prime when he was one of, if not the best, player in the world.

"If he's physically and mentally up for the challenge of Super League then it is only a positive and if he can get anywhere near where he was then it is going to be a treat for all Super League fans.

"I don't think he would have agreed to the challenge of playing if he didn't feel he was up to it.

"Steve Price is a smart coach and was instrumental in bringing him out of retirement and I am sure it will be a positive outcome for everyone."

Australian Associated Press