A 6-1 loss to Real Madrid which all but eliminates the Royal Blues from the Champions League was followed by a 5-1 reverse to Bayern Munich in the Bundesliga last Saturday.
Following on from a draw with Mainz, Schalke's form has slumped and Keller is seeking answers.
"We need to look forwards and provide the right answer on the field," said the Schalke coach. "We've dealt intensively with our mistakes from the game in Munich."
Aside from that game, Keller has also had an in-depth look at Hoffenheim's last match - a 6-2 triumph over Wolfsburg last Sunday.
Not the number of goals scored, but rather those conceded were of particular interest as Keller seeks a way of beating Hoffenheim and picking up three points to keep his side on course for a place in the Champions League next season.
"They're very susceptible at the back," he said. "We've got to manage to find the right balance between defending and attacking."
That is the conundrum also facing Hoffenheim coach Markus Gisdol.
His side have the third-best attack in the division with 52 goals scored, but also the third worst defence with 48 conceded.
For as long as they can continue to score at least one more goal than their opponents, like in three of their last five, all unbeaten games, Gisdol will be happy.
At the same time, he is not going to get carried away, even if the gap to the European places is now smaller than the one to the bottom three.
"We're not looking at the league table," he said. "We're just taking things week by week.
"All of my players are giving it all they've got to be in my starting XI and they all know they are being judged on their performances, and nothing else."
Gisdol is likely to name the same side which crushed Wolfsburg last weekend, meaning a second straight appearance for Anthony Modeste.
Jefferson Farfan is a doubt for the hosts with the Peruvian unable to train with a knee injury, while Kyriakos Papadopoulos is suspended after picking up a red card against Bayern last weekend.