Clint Dempsey looked to have secured the Stars and Stripes' qualification for round two after his late goal, but Silvestre Varela headed home with the last attack of the game to keep Portugal in the tournament.
However, Friedel suggested that Jurgen Klinsmann's side squandered a perfect opportunity to progress.
Friedel told BBC Sport: "USA were 20 seconds away from going through to the next round ahead of Germany. They just needed to keep the ball. Michael Bradley, one of our most experienced players, loses it which gives Cristiano Ronaldo a chance.
"It's a great ball and a great finish, but now USA are in a dangerous position, and it could come down to goal difference against Ghana - who look a better side than Portugal on this evidence."
However, both Germany and the USA can go through with a draw in their final game.