The Citizens are said to have identified the 41-year-old as their 'favourite candidate' to succeed Txiki Begiristain, who is set to depart the Etihad Stadium at the end of the season.
Begiristain had initially planned to step back from day-to-day operations at Man City when he turned 55, but he became so invested in the club's project and working alongside manager Pep Guardiola that he decided to extend his stay until his 60th birthday, which he celebrated in August.
The Spaniard joined the Citizens in 2012 in a move that reunited him with CEO Ferran Soriano, who he worked with during a successful spell at Barcelona.
He has since been an integral architect of Man City's rise to dominance in English football, particularly while working alongside Guardiola, with the club winning a total of 22 trophies across seven different competitions.
It is understood that Begiristain's decision to leave has been made with full knowledge and endorsement of Man City's hierarchy, and he will continue with his duties at the club during a handover period for the first six months before a successor is appointed.
Man City reach agreement to hire Sporting's Viana
The man set to replace Begiristain is Sporting chief Viana as multiple reports, including one from journalist Fabrizio Romano, claim that Man City have 'completed' an agreement to hire the Portuguese as their new director of football.
Viana is set to arrive at the Etihad in 2025, but The Athletic reports that his move to England could be announced as early as next week.
As a player, Viana earned 29 caps for Portugal and also represented the likes of Sporting, Newcastle United and Valencia at club level over a 15-year period before retiring in 2016.
He has since gained sizable recognition for his work as a director of football, spending just six months in that role at Belenenses before joining Sporting in 2018.
Viana has overseen a number of high-profile incomings and outgoings at Sporting, with Bruno Fernandes, Manuel Ugarte and Pedro Porro among those who have departed for significantly higher fees than they were signed for.
The likes of Ousmane Diomande, Morten Hjulmand and Viktor Gyokeres - Sporting's goal machine who has recently been linked with Man City - are among those who currently star in Ruben Amorim's first-team squad.
Interestingly, Premier League champions Man City will travel to Portugal to face Primeira Liga holders Sporting Lisbon in the Champions League on November 5.