After 4½ years in Serie A with Juventus and Inter Milan, the Frenchman has returned to England amid suspicion that his body may no longer be able to withstand the rigours of the game here.
Related ArticlesPatrick Vieira completes Man City moveWenger nearly re-signed VieiraAlan Smith: Vieira gamble a test of Mancini's judgmentVieira key to City aspirationsTransfer TalkSport on televisionFormer Arsenal team-mates Lee Dixon and Nigel Winterburn, who witnessed Vieira at his imperious best during the club's dominant period of the late-1990s, have both suggested that City have signed a player whose best days are firmly behind him.
But having arrived in a snowbound Manchester with the temperature gauge plunging beyond -10C, Vieira has insisted that the one person who has no doubts about his hunger and ability to perform is himself.
He said: "I have nothing to prove to anybody, to Dixon or Winterburn. I just have to believe in myself. What they say doesn't motivate me any more. Everyone is allowed to give their opinion, there are thousands of opinions.
"I spoke to the Man City legend, Mike Summerbee, only this morning and he told me that he played until he was 40, so hopefully I will play on until I am 40.
"I might not be as quick as I was at 20, but my brain is still going really fast. Football is not all about running or speed, it is about using your brain and I have no doubt that I can cope with it, no problems. I don't want to stand here and explain myself because talk is not the reality. Only what happens in the pitch matters, so we will see what happens."
The fact that Vieira is Roberto Mancini's first signing as City manager offers a key pointer towards the Italian coach's blueprint at Eastlands.
Vieira helped Mancini secure his second and third titles at the San Siro having arrived in an £8 million transfer from Juventus. The dominant figure who helped Arsène Wenger transform Arsenal's fortunes repeated the trick for Mancini, who has identified Vieira's leadership qualities and winning mentality as crucial additions to a City squad requiring a top-up in both areas.
Harry Redknapp wanted to bring those qualities to Tottenham, but Vieira admits his Arsenal past proved an obstacle he could not overcome. He said: "So many clubs were interested in me. Redknapp is someone I admire a lot and I like the way that he has been managing his team. He has been really successful with Portsmouth and is doing well with Spurs. I like him, but it would have been difficult to go as an ex-Arsenal player."
Vieira's last kick in English football was the match-winning spot-kick for Arsenal in the 2005 FA Cup Final penalty shoot-out against Manchester United.
Battles with United captain Roy Keane defined Vieira's previous stint in England and, while the Irishman has vacated the stage, United remain the foe that Vieira and City must topple to achieve their lofty ambitions.
Vieira said: "I remember my last kick for Arsenal, that is a good memory and maybe a good omen. Now that I am back, I want to win the Premier League and I think we can do it this season. We are not too far behind because at Arsenal, we won the league when we were 15 points behind at Christmas, so anything is possible.
"United don't look as strong as they used to, but I haven't come here just to topple United. I have come here because I really believe in the ambition of the club. Why do I believe we can win the league? Because I don't believe there is another team in the Premier League that has the quality of strikers that we have."
Vieira will meet up with United again in the Carling Cup semi-final later this month and, having been taunted by a chant from the United supporters ever since his stray pass led to Ryan Giggs's memorable goal in the 1999 FA Cup semi-final, he admitted that he was relishing having his ear drums battered again at Old Trafford.
Vieira said: "I've missed it, so it will be nice to hear it again. Playing against United was always exciting and I don't mind the chant."