Jurgen Klopp on Saturday vowed to turn around Borussia Dortmund's dire Bundesliga form in 2015 after their tenth defeat of the season left them second from bottom of the table.

Dortmund have the most defeats in Germany's top flight at the halfway stage with just 15 points from 17 games following Saturday's 2-1 loss at fellow strugglers Werder Bremen, who climbed off the foot of the table.

Dortmund will finish 2014 back at the bottom if Freiburg score and pick up a point against Hanover 96 on Sunday, when the Bundesliga starts the winter break.

But Klopp insists the 2013 Champions League finalists are not yet relegation candidates, despite their precarious position in the table.

"I wouldn't write us off yet," head coach Klopp insisted with the Bundesliga to resume at the end of January.

"We have three weeks to prepare ourselves for the second half of the season. We have played the worst first-half of the season of our lives, it's a catastrophe, but life goes on.

"Nothing much worked in the first-half and things only improved a little bit after that. We have tortured ourselves so far, but the season isn't over yet.

"We must, and we will, improve, we have shown a lot of weaknesses in the first half of the season, but we're not as weak as that.

"We need to recharge our batteries and fight back in the new year."

Borussia, who face Juventus in the last 16 of the Champions League in February, fell behind with just three minutes gone when Bremen's 19-year-old striker Davie Selke curled in a superb goal from 15 metres out.

Selkie then turned provider by outsprinting Dortmund captain Mats Hummels to put in a great cross which Bremen midfielder Fin Bartels converted on 62 minutes.

Hummels pulled a goal back when he headed home unmarked a corner from fellow Germany international Ilkay Gundogan on 69 minutes, but it was no more than a consolation.

Having won the 2011 and 2012 German league titles, then finished runners-up to Bayern in the last two seasons, Dortmund now peer up at Pep Guardiola's Munich from near the foot of the table.

Bayern are set to finish the weekend at least 11 points clear -- a new league record and Guardiola has said Dortmund's dire league form serves as a warning.

"When I see Dortmund, I always think: 'Okay. Pep, this can happen to us. This is a lesson for me. Bayern can also lose," Guardiola told reporters before his side's 2-1 comeback win at Mainz on Friday.

"To prevent this situation we must always try to improve."

Klopp should be able to welcome back key attacking midfielders Marco Reus and Henrikh Mkhitaryan during January's winter break with the pair having missed recent weeks with an ankle and thigh injury respectively.