Kwesi Appiah's men got their campaign under way on Monday and suffered a 2-1 defeat to the United States, falling behind to Clint Dempsey's goal inside the first minute.
Germany were in rampant form in their opener, beating 10-man Portugal 4-0, with Thomas Muller netting the tournament's first hat-trick.
Gyan is under no illusion that Germany will provide a serious challenge and he has urged his colleagues to improve.
"We hope to be more focused in our next match," he said.
"We've got time and we're professionals.
"We need to sit down, take a long hard look at our errors and work hard. We have to regain our focus and not let nerves get the better of us.
"It's going to be a difficult match but we need to stick together more than ever and play our game.
"Germany are the group favourites and their morale will be high after beating a team of the calibre of Portugal 4-0.
"We won't be feeling quite so good but we'll be determined to do ourselves justice."
Following the unconvincing performance against USA, former Ghana star Stephen Appiah has revealed that the coach will be making changes to his side.
"First games are always very difficult," he told Accra-based Joy FM.
"You'll see changes on Saturday. I have spoken to the coach. We have been talking."
