Marcos Rojo is preparing himself for a tricky afternoon when he attempts to nullify the threat of Sergio Aguero in Sunday's Manchester derby.
Aguero has scored nine times in nine Premier League outings this season for defending champions City and Rojo is well aware that stopping the 26-year-old - with whom he played during Argentina's run to the World Cup final this summer - from adding to that tally this weekend is a big ask.
"It's crucial to defend well against Sergio," the Manchester United defender told MUTV as he prepares for his first taste of a Manchester derby.
"Everyone knows he is a very fast player who can inflict damage.
"He's very good at getting into dangerous positions. You need to be very focused and concentrated on his movement and be very aware of where he is and where he might put himself.
"You need to do throughout the 90 minutes."
A victory at the Etihad Stadium on Sunday would hoist United one point behind City.
Rojo added: "Sunday's game is very important. City are a direct rival in the league.
"A win would be very important for confidence for the next few matches and would help us in a big way to carry on amassing points."