Borussia Dortmund coach Jurgen Klopp believes that it will be "difficult" for his side to qualify for the Champions League quarter-finals.
The defending German champions will head into the second leg of their last-16 tie against Shakhtar Donetsk levelled at 2-2 from the first leg played in Ukraine last month.
"It will be difficult for both teams," UEFA.com quotes him as saying. "In the first leg we saw that both sides are here on merit and they have high quality.
"The first leg decided nothing. Our position is maybe a bit better, but no more than that. I'm not worried about us making mistakes.
"There is no such thing as a football match without mistakes. It's about performing so well that your mistakes don't matter in the larger scheme of things."
Dortmund warmed up for Tuesday's game with a 3-1 home victory over Hannover in the Bundesliga on Saturday.
