Germany, on three points, must win their final Group D match against the Africans, who top the group on four points, to guarantee they advance to the next round.
A defeat or draw could see them eliminated at the group stage for the first time in the tournament's 80-year history.
"We know there is pressure here that a potential major flop, a disgrace, could be looming, that we could fly out in the first round," said central defender Arne Friedrich.
"But we just have to shut out those thoughts," he said. "We have to be clear about the fact that we have a very tough team and excellent players."
Germany are among the most decorated teams of the world's biggest football tournament.
Apart from winning the trophy in 1954, 1974 and 1990, the Germans have played in four more finals (1966, 1982, 1986, 2002) and have finished in third place on three other occasions (1934, 1970, 2006).
PRESSURE MOUNTING
Germany's youngest World Cup team in 76 years looked to be cruising when they crushed Australia 4-0 in their opening match but then slumped to a surprise 1-0 defeat to Serbia, leaving them in need of a victory against Ghana to be sure they avoid elimination.
"We have absolutely no concerns. We have to maintain our calmness and we know the pressure is growing," Friedrich said.
Germany will be without key striker Miroslav Klose, who was sent off against Serbia.
Cacau is his most likely replacement, but the Brazil-born striker said he had not been given the nod yet.
"Until now I do not know if I will play (on Wednesday), maybe it will be decided today or tomorrow," said the 29-year-old who only got the German nationality less than 18 months ago and had never dreamed of playing for Germany until a few months ago.
"That surprise and that dream is behind me now," Cacau said. "I am only focusing on this match. This game is too important."
