Barcelona's young team can learn from the setbacks they have faced in their LaLiga campaign and continue to improve, manager Hansi Flick said on Tuesday ahead of their Champions League meeting with Borussia Dortmund.

On Saturday, Barca put in an unconvincing display in a 2-2 LaLiga draw at Real Betis, which left them vulnerable to being overtaken by rivals Real Madrid in the title race.

The draw was not the ideal result ahead of a vital clash against Champions League regulars Dortmund, but Flick said it was natural for teams to have a slump in form during the season.

"In the end it all depends on how the season ends. We are convinced," Flick told reporters.

"We have to play the way we want to play and that's how we'll continue to improve. We are very clear about that. We are a very young team and that's normal.

"We have lost two points that have hurt us a lot but we have to learn from our mistakes. We are very united."

Wednesday's match at the Westfalenstadion will have added significance for Barcelona striker Robert Lewandowski, who spent four seasons at Dortmund and won two Bundesliga titles with the club.

The Polish striker has been in remarkable form this season, scoring 23 goals in 21 appearances across all competitions.

Asked if Barcelona were overly reliant on Lewandowski, Flick said: "We need Robert, but Robert needs the team. A player alone can never win a game by himself.

"I think when you look at how many goals he has scored so far, you can see that he is very lucky to have this team around him.

"But he has got a lot of quality as well. In the box is where he is most lethal and important... At the moment he is in a great form, great phase."

Barca will be able to call upon Ronald Araujo against Dortmund, with the defender back in the squad for the first time since suffering a muscle injury while playing for Uruguay at the Copa America in July.

However, Flick stopped short of providing a date for his return to action, adding: "We're all happy that Ronald is back. It's fun to have him with us in the training sessions.

"He's a great presence and the team needs him. He motivates his players and also me, the coach. I like him, I like what I see from him. He's a player that gives his all.

"We will see how he's tomorrow and how he will evolve over the course of the next few days and next weekend. I can't say anything now."