For the United States, a win guarantees advancing out of group play; a tie passes the baton to the game pitting England vs. Slovenia, whose result will determine the Americans' fate.
For Algeria, a victory is the only option.
"This match against the United States is like a final for us," Algerian defender Madjid Bougherra told reporters after the team's scoreless draw with England. "We've got to win it, and we're going to play with the same heart and determination. I promise it. We'll be like we were against the English: 11 warriors on the field, ready to fight until the end without letting down our guard to try to honor our country."
Algerian team consultant Zinedine Zidane, a legendary player who was born in France to Algerian parents and who spent his entire international career with Les Bleus, quite aptly represents Algeria's roster: Most have connections to France.
Many of the Desert Foxes, as Algeria's national team is known, played with French youth national teams before eventually pledging senior-level allegiance to Algeria; Algeria gained independence from France in 1962.
"I definitely believe we can get to the next round," Bougherra said. "We are getting better and know what we have to do - beat the USA in our final group match."
Despite an abbreviated World Cup history - this is the team's third appearance but first since 1986 - the team's assistant coach, Zoheir Djelloul, told the New York Times on Monday that the team is young, but has been brought together by experiences like the match against Egypt in Cairo and then in front of a packed home stadium.
The United States has the somewhat recent memory of its 2006 loss to Ghana, a match in which a victory could have propelled them out of the group stage.
"We have a great chance to get a win and advance to the second round," said U.S. team captain Carlos Bocanegra in a news conference. "It is important to us, because of that disappointment four years ago - it's not really extra motivation, but it's in the back of our minds."
Added Bocanegra: "You work so hard and train for so long for the World Cup and it can be over so quickly if you don't advance."
The Unites States trained Tuesday afternoon in Pretoria, about 45 minutes north of Johannesburg, but practiced without starting striker Jozy Altidore, who missed the session with an upset stomach.
Altidore is expected to be available Wednesday, but attacker Robbie Findley will be sidelined after collecting his second yellow card of the tournament against Slovenia.
U.S. coach Bob Bradley could start forward Edson Buddle alongside Altidore, but might bump Clint Dempsey forward from the midfield.
Throughout its match, the United States will be updated with England-Slovenia scores, knowing exactly what result is needed each minute of the way.
"I think for us, the concentration is just on getting ready for the match," Bradley said in Wednesday's news conference. "So many things can happen along the way, so we've not put much thought into the final way of determining things."
Contact staff writer Kate Fagan at 856-779-3844 or firstname.lastname@example.org.