Barcelona return to the competition after beating Alaves in La Liga at the weekend, but Flick knows his side must raise their level against Unai Emery's team following their defeat to Paris Saint-Germain.

The Barcelona manager praised Emery's work at Villa and expects a difficult encounter against a side he believes are among Europe's best organised teams.

"Unai Emery is one of the best managers in Europe. I really like the way his team play. They're confident on the ball and when building from the back, and I like their defensive structure," Flick said.

"They've got everything very well organised. Jackson is performing at an incredible level. It'll be a tough match against a great manager."

Flick also dismissed suggestions that Barcelona are struggling against the biggest teams, pointing to their 11 consecutive victories earlier in the season.

"Against Real Madrid the result could have been different, and the same against PSG. At this level, anything can happen. We've won 11 matches in a row," he said.

"We can make history and we're working towards that - to win La Liga and the Champions League. We've got the quality."

The German also defended Balde, who has struggled for regular playing time with Joao Cancelo currently enjoying an excellent run of form.

Flick admitted the young left-back needs to rebuild his confidence but insisted he remains committed to helping him improve.

"When you don't play often, you lack confidence. I see him training well, but we have to decide what's best for the team, and Joao Cancelo is in great form," he explained.

"I respect him a lot. He's young, but he's a great person and a very hard worker. I'll help him regain his confidence."

Gavi is another player waiting for more opportunities, but Flick stressed that the midfielder remains an important option.

"We all know his quality and Gavi is always an option," he said, adding that the most important thing was for the midfielder to maintain his confidence.

Flick also provided an update on Andreas Christensen, who has returned to training but is not yet ready to be considered fully fit.

"He's fine, but we'll have to wait until the weekend," Flick said.

Barcelona continue to deal with several defensive injuries, although Flick was encouraged by the performances of his available players against Alaves, including Frenkie de Jong and young defender Brian Farinas.

He also praised the understanding between Farinas and Lamine Yamal on the right flank, suggesting the youngster could feature against Villa.

"They link up well, they're friends, and they did very well against Alaves. Farinas is an option for tomorrow, but there are others," he said.

Raphinha has also impressed Flick with his performances this season, with the Barcelona captain adapting to different attacking roles, including the possibility of playing as a centre-forward.

"He's playing at a fantastic level, with strengths that suit us very well. He's very focused and adapts to the opposition by looking for spaces to attack," Flick said.

"He's our captain. He's shown his quality right from the start of the season. I'm very happy to have him performing at this level."

Report: Sir Jim Ratcliffe's 'wage war' could see Kobbie Mainoo leave Man Utd