Niko Kovac was left to lament wasteful finishing and some bad luck after Borussia Dortmund went down 2-0 to RB Leipzig.

Dortmund had 25 shots, getting nine of those on target, at Red Bull Arena on Saturday.

Yet they slumped to a defeat that leaves them 11th in the Bundesliga, with Xavi Simons and Lois Openda on target for the hosts.

Dortmund accumulated 3.11 expected goals and hit the woodwork three times, with Leipzig more clinical, converting their two goals from 1.78 xG.

"This is a catastrophe. And not the standard I set for myself," Kovac told Sky Sport.

"It's unbelievable. I can't explain it either. The ball just wouldn't go in today. The fact is: We didn't score the goals and left the pitch as unfortunate losers today.

"We have to score at least three or four goals."

Dortmund were Champions League finalists last season and have also made it to the quarter-finals this year, but their woeful domestic form has left their participation in the competition next season in question.

Midfielder Pascal Gross said Dortmund needed to be rational about their hopes of returning to Europe's biggest stage, adding: "We have to win games. It's slowly becoming unrealistic.

"First half was weak, second half we have to score the goals. We're in 11th place. I'm not going to say it now, 'We'll reach the Champions League'. You can always talk a lot. Today we didn't make it.

"It [the performance] was extremely bad, because once again we have problems after the Champions League. That really annoys me. I think consistency is a huge quality in football. We're lacking that. We can't play at a certain level every three days."

Dortmund also face an anxious wait to learn the extent of midfielder Marcel Sabitzer's knee injury after the Austria international limped off the pitch in tears early in the second half.

"I don't know exactly what happened. In any case, he has knee pain and we now have to wait and see what exactly happened there," Kovac said.

"I can't say if it's a long-term injury and I don't want to throw any speculation into the room. We'll have to wait and see and the investigations will then bring the result."

Dortmund next host Mainz on March 30, but defender Nico Schlotterbeck is not confident of their chances of pushing for European qualification.

He said: "It's difficult. It's almost impossible.

"The chances are very slim right now. We'll try our best, of course. After the international break, we have to attack somehow."

According to Opta's predictive model, Dortmund are now more likely to finish in 11th place than they are in any other position.