But he refuses to believe it is a task beyond them.

Skinner rejected claims his side were naive in not shutting the game down after they had twice fought back from conceding goals to former Chelsea star Pernille Harder, even though the first came after just two minutes as Bayern executed their gameplan to perfection.

Instead, he preferred to look at the positives of a match that eventually turned against them thanks to an 81st-minute strike from Momoko Tanikawa.

"I wouldn't call it a naivety," said Skinner. "There's going to be a little bit of learning in any game, especially when you're playing a quarter-final of the Champions League.

"I'm frustrated with all three goals. I don't think they had to work particularly hard to earn them.

"But what I know about this team is that they will be open and honest with that and obviously we've got another leg to try and fix it and turn it around.

"We have belief. Of course we do. There is no point going to Germany if we don't."

Nevertheless, Bayern coach Jose Barcala said he expected United to play with a "really aggressive high press" and set his team the task of getting behind them immediately.

His players carried out their instructions to perfection. Arianna Caruso played the pass into the space between United's defence and their penalty area and Harder outpaced skipper Maya Le Tissier to score, just as she did in the second half when eventual match-winner Tanikawa provided the pass.

"He has just won the game 3-2, he is going to say that," said Skinner, when it was pointed out Barcala had said Bayern felt comfortable in the periods of the game where United tried to make them feel uncomfortable.

"Our challenge is to make them feel way more uncomfortable."

Skinner's counter to the idea his side may have been better advised to drop slightly deeper to prevent Harder making those runs was sound.

"There are two mistakes in there from us," he said.

"If you get pressure on the ball, you can't play the long ball. They tried it a few times and played the ball out of play.

"It worked for them tonight but if I stop those two chances, they don't score."

It sounds simple. But execution is key at the highest level. If you don't do that properly, you will get punished.

There are a number of minor details to explain why United came out on the wrong side of a tight result.

One of them is unquestionably squad depth.

Take the case of Japan midfielder Hinata Miyazawa, who played in the final of the Asian Cup in Sydney on Sunday, then travelled back to start for United.

By contrast, Tanikawa, who did not get on the pitch against Australia, started on the bench for Bayern, who were mindful of the effects of jetlag and wanted the midfielder to make an impact, which she did, by setting up Harder, then scoring the winner.

Skinner simply does not have enough players to rotate like that.

It makes the next few days, which feature another Old Trafford outing against Women's Super League leaders Manchester City on Saturday before the trip to Germany for the second leg with Bayern next Wednesday (17:45 BST), particularly tough.

"We've played the most football in Europe this year, and we've got a really small squad right now, so it will challenge us," said Skinner.

"It will take us to the depths. But the carrot is there for us.

"We expect it to be difficult. You can kind of trench your mind into what you must do.

"That's why my players are at Manchester United. If they didn't want to do it, they wouldn't be at this club. They're going to give it absolutely everything."