Troisi, 29, is considering joining the club after his contract with cross-town rival Melbourne Victory expired at the end of last season.

Mauk, 21, who left City in January last year, is much closer to a return under new coach Warren Joyce.

The pair would form a homegrown midfield fulcrum to rival many in the league. But Troisi's move would be acrimonious.

He would be the highest-profile player to switch between the two clubs since Harry Kewell extended his playing career in the red and white stripes of Melbourne Heart in 2013.

After impressing in the Victory's run to the A-League grand final last season, Troisi hoped his form at the 2017 FIFA Confederations Cup might see him return to European football - or earn a marquee contract at Kevin Muscat's club.

The attacking midfielder claimed Victory didn't offer him that deal - a claim the club privately deny.

The 29-year-old was on the brink of a move to Israeli club Maccabi Haifa - even pictured holding their scarf - before he decided against a move.

Meawnhile, Mauk's deal is more straight-forward. The midfielder left City 18 months ago in a swap deal with Adelaide United for Osama Malik.

As City's fortunes dipped, Mauk became an A-League champion after earning a place in United's team that emphatically won the 2016 grand final over Western Sydney.

Mauk's form won him a Socceroos call-up and a move to Netherlands-based NEC.

But he wasn't able to land a first-team role in Holland and signalled his intention to leave the club after it was relegated in May.