"Brad will no doubt play a very valuable role in mentoring young players in the Roosters squad," Greenberg said at a nines event in Sydney today. "I have no doubt there will be many players excited to play with him and also against him."
It hasn't stopped plenty of detractors saying it drags down the credibility of the tournament to have someone who last played in the NRL nearly 10 years ago. He will be 42 when the nines kick off.
"When you're coming on 42, you don't really care what other people think," Fittler said. "That's one of the handy things. They haven't seen me play. Hopefully they comment after and will reassess what they will think.
"A lot has changed [since I last played]. Training with intensity definitely hurts. There are some things working against me a little bit to the point where the body breaks down but the Roosters have been great.
"Hopefully the players can learn something from a guy who played a couple of eras ago. They are good kids and we have a couple of internationals in there. Let's see what happens."
Playing alongside Fittler is something Roosters centre Shaun Kenny-Dowall never thought he would get the chance to do. Fittler was one of Kenny-Dowall's heroes growing up.
"He's been unreal," he said. "He's still really fit and is a natural-born leader. He's still got the skill so it's an exciting prospect and I'm glad he's on our team.
"I think [the criticism is] something he will be excited about. It's a challenge. He obviously feels he's up to it and the results will show in his performances."
The Warriors have been installed as favourites by some bookies but no one really knows what teams or approach will work given the newness of the event.
The Warriors were the only team not represented in Sydney today and were conspicuous by their absence - nines disciple Willie Mason couldn't resist a pop when he quipped, "good of the Warriors to turn up".
The Auckland-based club are involved in a two-day camp and offered to send a player outside their top 25 but organisers of the Sydney event turned it down.