The Red Devils welcome City to Old Trafford for the 169th Manchester derby on the back of a poor recent record against their local rivals.
United last beat the Citizens in the Premier League on December 9, 2012 at the Etihad, having lost the four derby meetings since then.
Van Gaal’s first taste of derby action ended in defeat when Manuel Pellegrini’s men emerged 1-0 victors at Eastlands in November last year.
But the Dutchman claims this team is very different from the one that was bested by Sergio Aguero’s 63rd-minute goal in the reverse fixture and says his players have since evolved as a group, as evidenced by their impressive run of results that followed.
United have lost just twice in the league since that loss to City and have climbed above the defending champions, who are next in action against Crystal Palace on Monday night.
“It was another Manchester United [last November], I believe,” Van Gaal told reporters. “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. Our performances show that, so it’s not the same Manchester United.
“Of course it [confidence] plays a part in the spirit of the players. Now we are winning five games in a row, so everybody has to wait for the right moment.
“City still have one match in hand at the moment [against Crystal Palace on Monday]. When they lose points or if it’s a draw, then we will be even. They also have a better goal difference so they have to lose, then we are better than City.
“This next game is the decisive game. It’s like the game against Liverpool and the game against Chelsea – you have to win these kinds of matches.”