Die Mannschaft were comfortable 4-0 winners over their European counterparts, yet the Bayern Munich midfielder feels his side should not get too carried away with their win.
“It was important for us to take those three points [against Portugal], but that was all,” Gotze told FIFA.com.
“Our performance shouldn’t be overstated, as there were some things that simply went well for us. In some situations we were just lucky."
Yet the 22-year-old feels it will be a very different encounter against the Black Stars, who are desperate for points after their 2-1 loss to the USA.
“It won’t be easy given that Ghana now need three points no matter what,” said Gotze. “It’ll be a very tough game, but we can be confident about it.”
Gotze is aware that any slip-up could cost his side at the tournament, and insists the German squad knows what is expected of them and will stick to their tried-and-tested formula.
“We don’t have many matches at this tournament, so we’re trying to go into each one of them with a high level of concentration,” he said.
"In these conditions it’s important to play rationally, stay focused and play football our way.”
“It’s really important that we cover every area of the pitch and always pick the right moment to move forward.
“Each of us knows what we have to do out there,” he concluded.
The Germany-Ghana clash is scheduled for 9pm on Saturday evening.