Manchester United striker Javier Hernandez says his team cannot underestimate rivals Manchester City in Sunday's Premier League clash.
In what will be the 160th meeting between the clubs, the 23-year-old insists the champions need to be at "100%" to gain all three points.
"Manchester City are doing very well, they've improved a lot but, in my mind, we only care about us," Hernandez said.
"We don't underestimate any team, we always expect them to be difficult."
He added: "City have a good manager. They've spent a lot of money and are doing great but I think, with the history of a club like Manchester United, we know most teams want to win against their rivals.
"We need to be at 100% because both teams want to win this game."
City are currently top of the Premier League table, with United two points behind.
The two sides have already met this season in the Community Shield, with Sir Alex Ferguson's men running out 3-2 winners at Wembley in August.
Since then Roberto Mancini's side have scored at least two goals in every Premier League game - but they have only won at Old Trafford once since 1974, a 2-1 victory for Sven-Goran Eriksson's side in 2008.
And Hernandez added: "It's a very big game for us and the city of Manchester and both sets of fans. Manchester City are at the top and Manchester United always want to be at the top.
"It'll be a very, very big game and hopefully we can get all three points."