England midfielder James Milner has completed his move to Manchester City from Aston Villa on a five-year deal.
City have also announced that Stephen Ireland has moved to Villa Park as part of the deal, reportedly worth £26m.
Milner, 24, will not be able to play in City's Europa League game at FC Timisoara but is available for Monday's Premier League visit of Liverpool.
"He can improve and be a great player for Manchester City for a long time," said manager Roberto Mancini.
Milner, who scored in Villa's 3-0 opening day Premier League victory against West Ham United, passed a medical on Tuesday before completing the move on Wednesday after paying visits to the City of Manchester Stadium and the club's Carrington training ground.
"It didn't take too much selling by the boss when you see the players who are already here and the plans for the club," said Milner.
"The last thing he said to me was 'be ready for the next game', and then he said 'be ready to win the Premier League', and that's my ultimate aim - that's what I want to do and why I'm here.
"There's a lot of competition to get there, it's where we all want to be.
"I'm ambitious and I want to win trophies here. I believe this is a great place to do that and I believe we will do it. Hopefully, sooner rather than later."
City did not say how much it paid for Milner, but an outlay of more than £25m would take the club's spending to almost £150m since May.
Milner - the current Professional Footballers' Association young player of the year - joins Yaya Toure, David Silva, Jerome Boateng, Aleksandar Kolarov and Mario Balotelli in moving to Eastlands this summer.
"I am very happy to have James with us," stated Mancini. "Everybody knows we have admired him for some time.
"He is an excellent midfielder, who can play in a number of positions.
"This is important for the team, and I am looking forward to seeing him play for us. We have a very strong squad, and this signing is a very important one for us.
"James he is already a very good player, who has proved he can play at the very top level. But he is also young and a good character, I think he can also improve and be a great player for a long time."
The Italian indicated that the arrival of Milner will be the club's final signing before the transfer window closes at the end of the month - but defended City's sizeable outlay on new players.