City took the honours in the last derby clash at the Eithad Stadium in November when they prevailed 1-0 thanks to Sergio Aguero???s goal.
The Premier League champions dominated that game as United registered just two shots on target, but Van Gaal???s side have improved since then and notched their fifth straight win when they beat Aston Villa 3-1 at home on Saturday, leapfrogging City in the Premier League table as a result.
“Of course form plays a part in the spirit of our opponents and also our players,” said the Dutchman.
“We have more confidence now and when they lose a point then it’s also sitting in their minds. Maybe it plays a role but that is dependable on the individual player and I don’t know the individual players of Manchester City so well.
“But we have a lot of confidence and we haven’t lost so many times at home.???
Van Gaal also believes his side will be unrecognisable from the side that slipped to defeat at the Etihad.
“It was another Manchester United, I believe,” he said.
“That was more in the start of the process and now we are in the end of the process. Now we have developed the team.
“I think also the confidence of our players is very high at the moment but also our performances show that so it’s not the same Manchester United.”