Dortmund's Sokratis in action against Berlin's Davie Selke. Photo: Srdjan Suki/EPA

BERLIN – The January transfer window gave misfiring Borussia Dortmund the chance to revise their squad for the Bundesliga home stretch while VfB Stuttgart took the more common approach of changing their coach.

Both teams have the chance to add some spring to their step at the weekend with Dortmund opening the round at in-form bottom club Cologne on Friday and relegation-threatened Stuttgart travelling to Wolfsburg on Saturday.

Dortmund, outside the Champions League spots in sixth, are now without top-scorer Pierre-Emerick Aubameyang, sold to Arsenal for a huge fee and replaced by Chelsea loanee Michy Batshuayi.

Coach Peter Stoeger will also make an emotional return to Cologne, the club he guided out of the second division and into the Europa League before being dismissed in December.

Stoeger has seen his new side stumble to three consecutive draws to start 2018 though he has not blamed squad uncertainty for the slips.

“I am reluctant to use that as an argument,” he said after his team rescued a 2-2 draw with Freiburg last time. “Within the team and our training sessions, I do not get the feeling the mood is negative.

“I could make it easier for myself and say that we have now drawn three games in a row because there is something else going on that is not overly pleasant. But I would not like to reduce it to that - certainly not for today's game.”

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Cologne have taken 10 points from their last four matches but remain deep in trouble, four points behind the play-off place.

“We can all read the table,” coach Stefan Ruthenbeck said. “We need points. Who we are facing is not what's important.”

Promoted Stuttgart, 14th and three points above the play-off spot, fired Hannes Wolf after their latest defeat last week and replaced him with Tayfun Korkut - who kept Bayer Leverkusen up despite a terrible end to the season last year.

“The club has achieved a great deal in the past year and a half,” Korkut told the club homepage. “That is very recommendable considering the (2016) relegation and the difficult phase which was connected with that.

“So far as the results are concerned, we are in a difficult phase right now, but we still have a gap to the relegation places. We need to widen that gap now.”

League leaders Bayern Munich, who hold a 16-point advantage at the top of the table, travel to lowly Mainz on Saturday.

Freiburg, 12th, host second-placed Bayer Leverkusen in a battle of form teams while Schalke, third, take on a Werder Bremen side which made transfer deadline moves in a bid to escape the bottom three.

Defender Sebastian Langkamp and attacking midfielder Milot Rashica boost their squad as new arrivals.

Midtable Hertha Berlin take on Hoffenheim while Saturday's late game pairs seventh-placed Borussia Moenchengladbach with fifth-placed RB Leipzig as both aim to close in on the top four.

Second-bottom SV Hamburg look to end a seven-game winless run at home to Hanover to conclude Sunday, after Augsburg welcome Eintracht Frankfurt in a duel of European hopefuls.