The Dutchman confirmed on Friday that David de Gea - who is reportedly a target for Real Madrid - will not feature in Saturday's Premier League opener against Tottenham at Old Trafford.
And Van Gaal, who has already added five players to the United side this summer, says the current situation could see him in the market for a goalkeeper.
“I think Manchester United have to always be a challenger or champion," he told the club's official TV channel.
“Of course we have problems still with the goalkeeper, so we need maybe two more players.”
