Hertha, newly-promoted this season, had a good start to their campaign before collapsing since the winter break, losing all their seven games in the league and German Cup.
Rehhagel, idolised in Bremen after coaching them for 14 years from 1981-95 and winning domestic and European titles, failed to turn things around in his Hertha debut last week with his team losing 3-0 at relegation rivals Augsburg leaving them in 16th spot, two points above bottom-placed Freiburg.
"For him this is a prestige game," Hertha assistant coach Rene Tretschok told reporters. "He is very emotional about this match.
"A win against Bremen would be the best thing for him now."
Rehhagel, 73, returned to the Bundesliga after a 12-year absence with the mandate of keeping the capital's only Bundesliga representatives up.
"We must get rid of that lethargy in our bones," Hertha goalkeeper Thomas Kraft told reporters after shouting at his team-mates during training.
"We have to become more aggressive. Everyone of our players must have motivation and passion now."
"As a goalkeeper I want to shake them so they wake up."
A defeat against Bremen would send Hertha deeper down the table and raise questions about whether Hertha's third coach this season, and arguably the most controversial choice for under-fire manager Michael Preetz, can turn things around.
