The Americans will be looking for a result against the European nation to secure a spot in the round of 16 in Brazil.
The U.S. national team was just seconds away from booking a place in the World Cup's round of 16, but Cristiano Ronaldo and Portugal made sure the Americans would need a win or draw - or some luck should they lose - against Germany on Thursday to advance out of Group G.
The Real Madrid forward delivered a beautiful cross to Silvestre Varela for the game-winning header in the 95th minute to earn a shocking 2-2 draw against the U.S. on Sunday. Now the Stars and Stripes will be looking for a result against FIFA's second-ranked team to guarantee a spot in the knockout round.
The match starts at 12 p.m. ET on ESPN.
U.S. fans will also be keeping a close eye on the result of the Portugal-Ghana match, which will be played at the same time on ESPN2. If the U.S. loses and those two teams draw, the Americans are through. Should the U.S. lose and either Portugal or Ghana get a win, then it will come down to goal differential.