With Rooney struggling and United unable to score, Van Gaal admits he doesn't know Martial's best position

Louis van Gaal showed his concern at Manchester United’s continued failings in front of goal as he warned his side must end their drought against CSKA Moscow next week.

United failed to score for a third successive game when they played out a scoreless draw against Crystal Palace at Selhurst Park on Saturday.

Van Gaal admitted his side were second best and insists they must bounce back when they resume their Champions League campaign at Old Trafford on Tuesday.

“Of course I am concerned [about the lack of goals], but today when you are not creating so many chances I cannot complain,” he said.

“Nevertheless we had chances which we could finish and then you win this game. And that is our history until now. So we have to improve that.”

Van Gaal denied the current run was affecting the mentality of his players.

“I cannot see that. I don’t think so. I don’t think they doubt their quality,” he said.