Manchester City boss Manuel Pellegrini insists Eliaquim Mangala will prove his class long-term.
Mangala was sent off in victory at Southampton on Sunday.
But Pellegrini says he will end up proving he was worth the outlay of £40 million to Porto.
He said: "There are two things here. Maybe a lot of players need more time to be really settled here in the Premier League, because it is a difficult league.
"And I don't think the foul that Mangala made at Southampton was not a good foul. It was a tactical foul, as he thought the player would score if he arrived at the ball.
"It just takes half a second to arrive late to the ball. He tried to win the ball because it was a very dangerous play for Southampton. He arrived late, it was a second yellow card, and he had to go. But I feel in the game he wasn't playing bad."
