The 24-year-old says Spurs will have their hands full in Sunday's contest at the Etihad Stadium when they come up against his international teammate.
The Brazil teammates could find themselves facing up against each other in midfield at the weekend, when seventh-placed Spurs will be looking to put some distance between them and City, who sit in eighth.
And the 24 year-old has warned his fellow Tottenham players there will be plenty of danger to combat in the encounter at the Etihad Stadium.
“Fernandinho is my friend,” he told Tottenham's official website. “I’ve played with him twice on international duty for Brazil. He’s a very good player, very quick in midfield. He can play defense and also play forward. He’s also great on the ball. We have to push him, put him under pressure and look after him – and not just him. City have lots of good players, but so do we and we will give everything.”
Spurs could potentially leap into the top four in the Premier League with a victory, and Sandro insisted a win is attainable if his side turns in a top performance away from home.
“I think it will be a difficult game, like every match,” he said. “We have to go and play with confidence from the beginning. We will need everything on the pitch because it’s a hard game to win there, but we have to do it. From the start of the game we have to push on, to fight for every ball, to be on top of City.
“A win would be great for us. Every match is important. Let’s go to try to win this match first. We can do it. We can win there.”