Phillip Cocu says Derby County’s focus must be absolutely spot-on ahead of Tuesday night’s Emirates FA Cup Fourth Round replay against Northampton Town at Pride Park Stadium.

The Rams and the Cobblers played out a 0-0 draw in the original Fourth Round tie at the PTS Academy Stadium last month.

The winners of the replay will face Premier League giants Manchester United on home turf in the Fifth Round of the competition in March.

Cocu says the Rams must approach the game against Keith Curle’s Sky Bet League 2 side with the exact same mentality as they displayed in Friday night’s 4-0 thrashing of Stoke City at Pride Park.

Northampton are enjoying a fine season in League 2 and a positive run of form in recent weeks has seen the Cobblers establish themselves as promotion contenders.

Speaking to RamsTV, Cocu said: “It is a big game for us.

“The result on Friday was a good result, we played an excellent game too, but Tuesday is a big game coming up.

“We have to be performing with the same level and desire as we did on Friday night against Stoke.”

He added: “It will be a difficult game for us so we have to approach it with the right mentality to try and get through to the next round.”

Tuesday’s clash against Northampton will be the first FA Cup replay at Pride Park Stadium for over ten years, with the last being Derby’s penalty shoot-out victory over Millwall in January 2010.