Rooney has been restored to his role as a central striker this season despite spending much of last term in midfield.
So far he has failed to find the net and has had no shots on target in two matches.
In Friday’s 1-0 Premier League win over Aston Villa, the United skipper only touched the ball in the away penalty box once.
Van Gaal has decided against buying a striker in the transfer market and seems to have an unshakeable belief in the 29-year-old.
“All the media has written for one year that I have to put him in the striker’s position so it is very amazing that after two matches you already are doubting your own opinion. I cannot understand that,” the United manager said in a spiky press conference on the eve of tonight’s Champions League play-off against Club Brugge at Old Trafford.
“I have always confidence in my players but we don’t have only Wayne Rooney in the striker’s position.
“We have also Adnan Januzaj, Chicharito (Javier Hernandez) and (James) Wilson so I don’t think we have a lack of strikers.”
Januzaj, a surprise starter on Friday, scored the only goal at Villa Park.
Van Gaal was far from effusive in his praise of Januzaj after the match, and the Dutchman again did not give the 20-year-old a ringing endorsement yesterday.
Van Gaal rejected the claim he has not given enough playing time to the Belgian, who lacks consistency according to his manager. “Adnan has eight starts last season and 14 substitutions (last season) so he didn’t have any chances? This is not true,” he said.
“The other players have no right (to start)? Only Adnan has a right? No. He has to compete with 23 or 24 other players.
“He is 20 years old. The characteristics of a young player is that he is not consistent. He has to show that. Maybe he can show it now this season. It is possible.”
Although Januzaj did start eight times last term, he failed to have the same impact as he did the season before when he was a shining star under David Moyes.
The Belgian failed to score for Van Gaal last season, but has no plans to leave.
“Last year was last year. This year is this year. I am happy at Manchester United,” Januzaj said.
On the face of it, United drew the easiest opponent possible for the play-off, which will be completed next week when Van Gaal’s men travel to Bruges.
The Belgian team will certainly not pose as much of a threat as Lazio or Monaco would have done.
But, wary of the consequences of failing to qualify for the group stages of the competition, Van Gaal admits there is a lot riding on the two-legged tie.
“It’s a lot of pressure because our aim and goal is to reach the Champions League,” Van Gaal said.
“All the players and the fans and the board want to participate in the Champions League but first you have to beat Club Brugge.”
Van Gaal refused to divulge whether goalkeeper David de Gea would be considered for selection after missing the last two games in light of Real Madrid’s interest in him.
“I don’t answer that,” he said.