Keller, 43, and Slomka, 46, find themselves in the uncomfortable position of knowing their futures are being discussed.

Both have fallen a long way short of their clubs' pre-season objections as the league breaks for winter on Sunday.

Hanover, 13th, are already ten points off a targeted top six spot to claim a European place next season after suffering their eighth-straight away defeat on Saturday.

Likewise, seventh-placed Schalke are already 16 points off leaders Bayern and any aspirations to challenge for the title have been hampered by their own erratic form.

Schalke's general manager Horst Heldt refused to back Keller -- who has been in charge since December 2012 -- after the Royal Blues dropped to seventh in the table after their goalless draw at Nuremberg.

"Overall, it's been a turbulent half a year," Heldt told Sky Sports after Keller missed the Nuremberg game with illness.

"It's important that we draw our conclusions and realise what we've done well and what we've done badly.

"That means the work of every individual is examined, including the coaching team. We do this every six months as a rule.

"There have been situations that we've not been so happy with."

Keller's future has been hotly debated in the German media.

"I didn't start that discussion and I'm not responsible for finishing it," said Heldt.

"We have to see how he's doing.

"Of course, the head coach should be here, we have already had a meeting without the coaches."

Slomka, who has been in charge since January 2010, is in a similarly uncertain position after his team lost 2-1 at strugglers Freiburg to leave them with just one win in their last 10 games.

"Christmas is the hardest time to make a decision like this," Hanover's director of sport Dirf Dufner told broadcaster Sport1.

"We will have more talks over the next few days."