The US should hope for a Portugal victory over Ghana. We have a much better goal difference edge over them.
I pick Ghana over Portugal, unfortunately. Their offense seems much more effective and dynamic.
I think we can beat Germany. Not likely, but we can.
If EITHER game ties - the USA advances (With a Por-Gha tie, we could lose 10-0 to Germany and still advance)
If the USA loses to Germany, and Port-Gha doesn't tie - it is far better that Portugal wins. The USA goal differential over Portugal gives quite a cushion.
The following scenario will actually let the USA advance (and less extreme examples too of course):
Ger -- 4
USA --1
Por -- 2
Gha --0
But forget all that bean-counting -- BEAT GERMANY! (...Or just tie 'em)