Manchester United go into one of the more important matches of Louis van Gaal’s 18-month reign with the club’s former manager, Sir Alex Ferguson, admitting he is worried about Jürgen Klopp’s restorative powers at Liverpool and Bastian Schweinsteiger reeling from the news that the Football Association have charged him with violent conduct.

Schweinsteiger will face a three-match domestic ban when United return from their final Champions League group match against Wolfsburg, when they might need to win to qualify for the knockout rounds. The Germany international caught West Ham’s Winston Reid with a forearm during Saturday’s game at Old Trafford and the FA has deemed it would have been a red card offence if the referee, Mark Clattenburg, had seen the incident. Schweinsteiger has until Thursday to appeal or he will miss games against Bournemouth, Norwich and Stoke.

The news came within minutes of Van Gaal admitting he was dismayed by United’s scoring problems after a run of five goalless draws in their last nine matches, but insisting “it was only a matter of time” before they put it right and expressing his confidence that they would not drop into the Europa League.

Van Gaal offered his support for Anthony Martial, whose initial scoring burst of four goals in as many games has been followed by one in the last 13, and the United manager said he was satisfied overall with the team’s performances.

“I am pleased. When I have to consider our season it was only the match against Arsenal [a 3-0 defeat] and the match against Crystal Palace [0-0] when we were not the better team,” he said. “Normally we create more chances than our opponent but you have to finish those chances because football is about scoring goals. As a manager you cannot be pleased when it’s like that. You have to score. But when you ask me about the performance as a team, mostly I can say that I am satisfied.”

Van Gaal’s squad arrived in Germany with an extensive list of absentees, prompting the Dutchman to include several youngsters and fringe players among a 19-man travelling party. Nick Powell, who has played only one game for United in the last three years, has been drafted in and there are also places for the teenagers Sean Goss and Cameron Borthwick-Jackson.

Wayne Rooney’s absence means Martial is the only recognised striker in the squad and Van Gaal is concerned that too much is expected of the Frenchman since his early glut of goals. “I think he is very talented but we have to say he is 20 years old,” he said. “We have to give him time and that’s always difficult when you are playing for a team like Manchester United because the expectations are very high.

“I am very convinced that he will continue with his performances, and that he shall score at the right moment again. But you cannot expect of a 20-year-old player coming to the Premier League that he scores every week.”

Ferguson has joined the team in Germany and, speaking at a seminar in London before flying out, the club’s former manager talked about the possibility of Klopp re-establishing Liverpool as a team that could possibly overtake United. “Even at Newcastle when they lost the second goal he goes over to Steve McClaren to congratulate him,” Ferguson said. “That’s class. And the work he did at Dortmund. He’s going to make a difference at that club with his personality, drive and knowledge. Things are looking up there. I’m worried about him because the one thing United don’t want is Liverpool to get above us.”

Wolfsburg, fifth in the Bundesliga, have never reached the Champions League’s knockout stages but are currently top of Group B. United are second but PSV Eindhoven could potentially leapfrog them by beating CSKA Moscow and the Wolfsburg manager, Dieter Hecking, was asked why a team with Van Gaal’s resources were not in a better position. “Because, thank God, money is not everything in sport,” he said.