Ronaldo joined Real Madrid in a world-record deal, while Tevez joined rivals Manchester City.
He said in The Sun: “We have to prove to everyone we can win this league again.
“We played well in parts against Birmingham, but there is more to come from us.
“It was the first game of the season and it’s always very difficult after playing a lot of games pre-season.
“When it comes to the atmosphere and intensity of the game, it’s a lot quicker than pre-season games.”
