Carlos Tevez wary of old partner in crime Cristiano Ronaldo

Carlos Tevez knows Cristiano Ronaldo is the man Manchester City must stop if they are to overcome Real Madrid and keep their Champions League campaign alive.

It is a cliche in football to label a game 'must-win' but Wednesday's match at the Etihad Stadium is exactly that for the hosts, with City obliged to defeat the Spanish champions if they are to avoid another group-phase exit.

Tevez spent two seasons alongside Ronaldo at Manchester United, where they won the 2008 Champions League, and the Argentine knows his City team-mates cannot afford to take their eyes off him for a second.

"Cristiano is one of the best players in the world and he will play in this game the way he always has done," said Tevez, whose side have picked up just two points from their four Group D matches to date.

"He does not seem to feel pressure, and there will be no added pressure just because he is back in Manchester.

"Once he gets a chance to face up to you and run at you with the ball he is very, very dangerous and he strikes the ball well, too."

Ronaldo has not played in Manchester since leaving City's sworn rivals United in 2009 and there is sure to be a hostile reception for a player whose 46 goals fired Madrid to last season's Spanish league title.

For all his achievements over the last 12 months, Ronaldo could once again find Barcelona's Lionel Messi blocking his path to this year's FIFA Ballon d'Or, which will be awarded in January.

Having played with both players, Tevez is ideally placed to weight up their respective merits, and he says he cannot look beyond his international colleague.

"I think it is only right if Cristiano does believe he is the best in the world," he said.

"Any guy who gets 37 to 40 goals a season has a right to believe that, and is one of the best in the world, but if you push me I am always going to go on the side of Messi."

Tevez's City career looked over a year ago, after coach Roberto Mancini banished him for refusing to come off the bench in a game at Bayern Munich, but he returned to play a key role in the club's Premier League title success.

Tevez spent almost six months out of the side before finally returning, but he says that the subsequent relocation of his family has given him fresh perspective.

"I have changed my outlook on life in general," said the 28-year-old, who scored twice in Saturday's 5-0 win over Aston Villa.

"A very important factor is the fact I have all my family here in Manchester, which makes me very happy.

"I am not worrying about the things I used to worry about. I am just concentrating on enjoying my time out on the field.

"My concerns, the things I concentrate on at the moment, are training and playing."