If Ghana somehow beat Germany today and assuming Portugal wins tomorrow, this will really become the Group of Death. Of course, there are still goal difference advantages (unless Portugal win by three goals, you'll still technically be in second place) but everything will be left to play for on the last day and you don't want that going into the Germany match.
A draw today wouldn't be the worst result from the U.S. perspective but, again, Germany would be fired up for that final match because they'd only have four points. If Portugal end the weekend with three points, they would win the group with a victory against Ghana if Germany can't beat the U.S.
Yeah, it now does seem pretty clear that a Ghana victory today is bad news for the US. However, some seem to want a tie today as opposed to an outright German victory.