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.

"It can change in one match and let it be against CSKA because we need a victory.

"We have to hope we score against Moscow, because then we are talking in a different way."

The former Bayern Munich and Barcelona manager used Wayne Rooney in the central striker role with Anthony Martial operating on the left.

Rooney had just one clear chance to score and van Gaal switched the two players in the second half, but conceded he remains uncertain where Martial's best position is.

"We don't know yet. He always played as at left winger at Monaco," van Gaal said.

"I have to see what is the best balance in the team and that's not so simple.

"I have to decide every week, depending on the game plan and the opponents.

"We have played with him in the striker position. It wasn't the first time for him but in Monaco he played almost always on the left."

United's supporters chanted for the team to attack, after a week in which Van Gaal's tactics were criticised as being unadventurous by former United player Paul Scholes.

But the Dutchman said: "The right of the fans is always there. It was the first time, apart from Arsenal we were not the better team away.

"They can sing that but the next game they shall sing in another way."

Palace manager Alan Pardew agreed United are playing in a different way this season and that they lacked attacking threat.

"It's a different style under Van Gaal, it's a very patient style. Incision is where they're lacking at the moment," Pardew said.

"United - and it doesn't happen very often - were probably fortunate to get a point.

"It was a shame we didn't win it but with the run we've been on we needed to take something, so the point was important for us."

Pardew, though, was fuming at the treatment handed out to Palace midfielder Yohan Cabaye who he believes was targeted by Van Gaal's side.

"I was a little bit frustrated. I said to the fourth official that Yohan had eight fouls on him today and three or four of them were a bit tasty," Pardew said.

"He was obviously a target for them to slow him down and I don't think he got a lot of protection from the referees.

"In fact I told my own team that should have been highlighted by some of our senior players, because he was targeted today.

"Of course if you're going to be fouled as many times as he was you're going to be frustrated, so I understand that.

"But without trying to sound too negative he still had a very influential performance for us."