Costa Rica beat the favored Japan 1-0 with a late goal on Sunday.

Keysher Fuller scored the match’s sole goal at the 81-minute mark, shooting from inside the 18-yard box and slipping the ball past the fingertips of Japan’s goaltender, Shuichi Gonda.

The goal was Costa Rica’s first of the tournament after losing 7-0 against Spain in its opening game.

After a stunning loss to Saudi Arabia in their first game, Argentina defeated Mexico 2-0 in the closely-watched Group C match.

Argentina’s two goals came courtesy of a long-distance strike from superstar forward Lionel Messi in the 64th minute and a shot to the top corner from midfielder Enzo Fernández in the 87th minute.

Argentina and Saudi Arabia now have three points each. The team that wins their third match in this round will likely head to the knockouts.

France defeated Denmark 2-1 with a last minute goal from Paris Saint-Germain star Kylian Mbappé, in what was a tight game between the two Group D teams.

Mbappé also scored France's first goal of the match. The win solidifies France's spot in the knockout round.

To qualify for the next round, Denmark will have to defeat Australia on Wednesday.

Poland defeated Saudi Arabia 2-0, putting the Polish team in Group C's top spot.

Saudi Arabia has the second highest number of points in the group thanks to its surprise 2-1 win over Argentina. Mexico and Argentina will face off later today, where Mexico could knock Argentina out of the tournament with a win.

U.S. national team coach Gregg Berhalter tried to keep the focus on Tuesday's game at a press conference as he faced questions about why the U.S. team's Twitter account removed the Islamic emblem from Iran's flag in a post Sunday. He also insisted his team had no knowledge of the post.

The U.S. soccer federation said it removed the logo to show support for those protesting in the country against authoritarian rule and its treatment of women.

Berhalter tried to keep the focus on the uniting power of sports and the World Cup, even as Iran called for the U.S. to be kicked out of the World Cup for altering its flag.

"Sport is something that should bring people together, bring countries together," Berhalter said. "When you look at the Olympics, to see all those countries competing at the same time, is a wonderful event. The World Cup is very similar, where people come from all around the world. Fans come from all around the world, and you get to compete on the field, as brothers, so sport does have the ability to do that."

U.S. captain Tyler Adams was criticized by an Iranian reporter for mispronouncing "Iran," which he apologized for, and he was questioned about discrimination in the U.S., saying it is everywhere but there has been progress. But he also deflected attention back to the game.

"Listen, we support Iran's people and Iran's team. But that being said, you know, we're laser focused on this match as they are as well," Adams, 23, told reporters. "We know how important this is for our progress of our team and what we want to do to prove to our country, you know, how hard we've been working. And we know they want to do exactly the same."

The U.S. must defeat Iran Tuesday to advance to the knockout stage of the tournament.

-ABC News' Karyn Rhodus