City say they have accepted a bid from Corinthians in excess of £40 million (Dh236m), with the club reducing their initial asking price for the striker on the condition that the Brazilian club do not sell him back to one of their major domestic or European rivals.
Andres Sanchez, the Corinthians president, said later that "nothing concrete" had been agreed and that City had asked for changes in the manner of payment and the total value of the transfer.
However, with Tevez's departure imminent, Vieira, a Premier League champion three times during his nine years at Arsenal, is convinced City's squad can compensate for the Argentine's departure.
"Of course Carlos is top class, and to lose him is a blow," City's new football development executive said. "But you can't keep a player if he doesn't want to stay. There are plenty of players in the squad to challenge for the title. Yaya [Toure], [David] Silva, [Edin] Dzeko: there are quality players. It is a chance for others to take extra responsibility and to be the stars. It happened when I left Arsenal, [Cesc] Fabregas came through to show how good he is. When Thierry [Henry] left, [Robin] van Persie has shown he can take it on.
"If Carlos comes to leave, it will be a sad day for the club, for the Premier League; he has been a fantastic player over the past couple of years. Like Cristiano [Ronaldo] leaving Manchester United, when they lost [Eric] Cantona: important players, but you find new players."
Last season represented a breakthrough year for City, who won their first silverware for 35 years and finished in third place in the Premier League. Vieira is confident that progress will continue without Tevez.
He said: "It's a big step and what's important is to maintain the Champions League spot for years and years and winning the league and winning the Champions League will come."
Vieira retired in the summer, playing his final game in May's FA Cup final victory over Stoke City, and has now taken up a new role behind the scenes.
He was speaking as City opened the public consultation period for their planned youth development and first-team training centre, including a 7,000-capacity stadium, which they intend to build on the Etihad Campus.
City are aiming to regenerate an 80-acre site and Vieira believes it will guarantee a fine future long after Tevez has gone, luring proven talents and promising youngsters alike to the club.
"It doesn't compare to anything I've seen so far," said the former Juventus and Inter Milan player. "It's the biggest project I have ever seen. Everything for the players to improve, to stay at the top and challenge any of the biggest clubs around the world: all the facilities you want will be inside. The facility here will create world-class players."
The Argentine striker is the favourite to fill the void at City, although Real Madrid would like to sign him from city rivals Atletico, along with Juventus. Like Tevez he is stocky, has a low centre of gravity and is outrageously skilled. Aguero was Argentina’s best player as they went out of the Copa America and has declared that he will not return to Atletico next season.
Reported cost £35 million (Dh207m). Chances of it happening 8/10
Udinese’s Chilean striker has been linked with Barcelona, Real, Napoli, Manchester United, Chelsea and City. And he might not even go anywhere, with his Italian side well placed financially and in the Champions League. The club’s chairman thinks he can be as good as Cristiano Ronaldo, which is why Barca appear to lead the race to sign him. Now that Chile are out of the Copa America, his future will become clearer.
Reported cost £45m. Chances 5/10
That the Argentine was initially in his country’s starting line-up at the Copa America, ahead of Aguero, Gonazalo Higuain and Diego Milito, speaks volumes of how highly he is rated. Provided the foil for Edinson Cavani, the Uruguayan who scored 26 goals for Napoli last season, and would fit into the same role alongside City’s Edin Dzeko.
Reported cost £25m. Chances 5/10
He may have been sent to train with the reserve side, but in Adebayor, City have a ready made replacement for Tevez under their noses. Whether he still has a future at the Etihad Stadium remains to be seen. On form, Adebayor is one of the most feared strikers in the Premier League but he recently went public in criticising Roberto Mancini, the manager.
Cost, free. Chances 2/10
* Thomas Woods