It's understood he will sit on the bench alongside Herbert during match-day, but his role won't extend to pulling on the boots again.
"I don't think so," Herbert said.
"We spoke long and hard and I think the difficulty for Chris is when is the right time to retire and I'm certainly not making that decision for him, but if he's part of the coaching staff it'll be 100 per cent what he's doing. Unless something dramatic happens."
Last season, Greenacre was expected to play the odd game in between coaching the attacking players in the squad, but when the Phoenix operated with limited funds in the wake of the ownership changeover, the veteran Englishman played every game of the campaign and netted four goals.
In other team news, Herbert said the club wanted to sign another striker before the season got underway, while there were minor injury concerns over Vince Lia and Jimmy Downey, who were expected to be on the sidelines for another three and five weeks, respectively.
Goalkeeper Mark Paston has had the screws removed from his leg - from a previous break - and will be out of action for five weeks, while there is worse news for Lucas Pantelis.
The 30-year-old hasn't played a regular season game for the Phoenix since he badly injured his knee in a warm-up game last year and has now suffered an infection in his knee.
He will undergo further surgery when the infection has cleared and Herbert said the left-sided player may never be seen in a Phoenix uniform as he enters the second and final year of his contract.
"I think there is a chance. Just medically they want to make sure that they do everything right and make the right evaluation for him. But it's probably not looking healthy at this stage."
Striker Mirjan Pavlovic has been loaned out to a club in Sydney for the pre-season, while youngster Cameron Lindsay, who missed out on a spot in the New Zealand under-23 side for the London Olympics, could also be sent somewhere on loan in the coming weeks.
The Phoenix are hoping to play seven to eight pre-season games before the A-League gets underway proper in early October, which could include a tour to India.
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