Dortmund are in good form heading into their Champions League tie against Barcelona. Photo: Martin Meissner/AP Photo

BERLIN  Borussia Dortmund kept a clean sheet in their impressive 4-0 Bundesliga win against fancied Bayer Leverkusen, which is good news for them ahead of Tuesday's Champions League opener against Barcelona.

"It was a good dress rehearsal. Against Barca we will also be without the ball for extended periods," midfielder Thomas Delaney said.

"It's important to keep a clean sheet. Ultimately, we win 99 per cent of our home games when we keep a clean sheet."

Even always-cautious coach Lucien Favre said "it is always good to win, also ahead of such a game," against the five-time European champions Barca.

Dortmund got back on track in the league after a surprise 3-1 defeat at promoted Union Berlin which had highlighted some weaknesses at the back and up front as well.

Dortmund have immense quality up front with Spain's Pablo Alcacer, who has scored all eight competitive match he has played in this season for club and country, English teenager Jadon Sancho as well as German internationals Marco Reus and Julian Brandt.

Mats Hummels has returned from champions Bayern Munich to bolster the defence, and the Dane Delaney received plenty of praise for his role as a holding midfielder against Leverkusen.

"Put in exaggerated terms, he was involved in 200 challenges and won 210 of them," sports director Michael Zorc said.

The right balance between solid defence and Dortmund's trademark fast attacks is needed even more on Tuesday against Barca even though Lionel Messi is likely not to feature for the Spanish champions.

Barca beat Valencia 5-2 on the weekend, with 16-year-old sensation Ansu Fati scoring his first goal as a starter and setting up the second.

The two sides have only met once before, with Barcelona winning the 1997 European Super Cup tie over two legs at the time 3-1, getting a 1-1 draw in Dortmund after winning the home leg 2-0.

The good news for Dortmund is that they should get some spaces because Barca don't defend with 10 players. Dortmund have often lacked ideas against such teams in the past.

Saturday's Bundesliga victory has fully restored morale in the German camp as the loss in Berlin had already led to questions whether they could really be a contender for the Bundesliga title and be a factor in Europe as well.

"There was pressure, we needed a good result," Zorc said.

The captain Reus added: "I hope this game gives us a lot of confidence. We didn't have that in the past weeks."

dpa