'Miracles happen', says Kovac before uphill Barca battle
In that season, eventual winners Liverpool scored four at Anfield in the return leg to reach the Champions League final, after a 3-0 loss in Catalonia.
Kovac said Barcelona were a better team now than six years ago, but told reporters "miracles happen all the time".
"We can remember the (Liverpool) game -- I can remember it. But that was then and now we're in 2024-25. We know the situation -- we didn't play well in the first leg," Kovac said.
"We want to show a different face tomorrow and we want to win. By how much, nobody can say now.
"Miracles happen all the time, but Barcelona have not lost a game in 2025, which makes the challenge much more difficult. It won't be easy."
Barcelona's last loss came on Christmas Eve. Since then, Hansi Flick's side have won 20 and drawn four matches in all competitions.
Dortmund midfielder Felix Nmecha said his team-mates "believed" in the comeback.
"With our fans behind us, anything is possible. We have to believe in it and we do believe in it," the 24-year-old German international explained.
Dortmund captain Emre Can did not train on Monday due to "muscular problems" and Kovac said: "We don't know if he'll be able to play -- it's quite possible that he will not."
Kovac, Dortmund's third coach this season after taking over in January, praised Barcelona's glittering forward line including Lamine Yamal and Raphinha, but singled out striker Robert Lewandowski.
Lewandowski won two Bundesliga titles and played in the 2013 Champions League final with Dortmund, before spending eight years at Bayern, where he was coached by Kovac.
He won the Champions League in 2020 under Kovac's successor Flick, now the Barcelona coach.
"He's a great professional," the Croatian said. "I've seen many good ones. But this guy? He lives, eats, drinks like a pro and does everything possible to stay fit."
Kovac, known for his focus on training and discipline, said anyone who hugs Lewandowski remarks "wow, what an Adonis".