Hansi Flick insists Barcelona will battle until the end to win titles, though he is unhappy with their recent form after just one win in six LaLiga games.

After a superb start to the season which saw them win 14 of their first 16 matches across all competitions, Barcelona lost their way domestically with Sunday's 1-0 loss to 15th-placed Leganes, a second home defeat in a row. 

They remain top of the LaLiga table with 38 points, though Sunday's opponents, second-placed Atletico Madrid, are level on points with them as well as having a game in hand.

To make matters worse for the Catalan side, Atletico have been in terrific form ahead of the highly-anticipated clash at the Lluis Companys Olympic Stadium, having won their last 11 matches in all competitions.

"What I can feel in the city and the supporters know what the team is like. We lost five important players. Dani Olmo and Pau Victor are the [new] signings. The team has improved and is focused," Flick told reporters on Friday.

"We are not happy with the situation, but we are going to fight until the end of the season. We want to win titles, but we know it won't be easy. But we want to win, that's what we want to do tomorrow."

Barcelona have won their last five meetings with Atletico in LaLiga and can equal the best run of consecutive wins over them in their history in the competition, achieved between September 2010 and May 2013.

They have also not conceded a single goal in their last four matches against Diego Simeone's side, and Flick says there will be little room for error if they are to win against Atletico.

"It's the end of the year. It's a great game. It's one of the best rivals. But today is December 20 and we're first in LaLiga and second in the Champions League. We are not bad. We lost some points against Las Palmas [2-1 loss] and Leganes, we have to recover them," Flick added.

"Tomorrow is another game. We have a young team and we have to fight and improve. We want to achieve great things. But we know it won't be easy. We have to start fighting tomorrow. We are playing against great teams."

Barcelona have suffered a blow with winger Lamine Yamal sustaining an ankle injury during their loss against Leganes. The 17-year-old Spain international is expected to be out for three to four weeks.

"We have to accept that he is injured and won't be able to play," Flick said.