Christian Pulisic nearly captured the entire story of the United States’ win-or-go-home match against Iran on Tuesday in the second minute, when he took off on a dangerous-looking run forward that came to nothing.

But after 37 minutes, seven shots and five chances that generated 0.42 expected goals but no actual goals (while allowing none, none and 0.00 to Iran), Pulisic truly exemplified America’s effort in this match: He put his body on the line to score the goal that would knock Iran out of the World Cup -- and send the U.S. to the knockout round.

Read more about how the USA's change in tactics earned them the win.

-FiveThirtyEight's Ty Schalter

The Group D matches are underway Wednesday morning in Qatar with France taking on Tunisia and Australia facing Denmark.

France is already qualified for the knockout stages, so the other three teams are competing for a place alongside them. A win for Australia, currently sitting on 3 points, would automatically qualify them for the next round.

Denmark and Tunisia are sitting on 1 point each, so they need to win and get some help from goal differential to qualify for the next stage.

U.S. forward Christian Pulisic was diagnosed with a pelvic contusion after colliding with Iran’s goalkeeper during a match on Tuesday, the U.S. men's national soccer team said.

Pulisic's "status is day-to-day," the team said in a tweet.

"I’ll be ready Saturday don’t worry," Pulisic said earlier in a social media post accompanied by a photo of the superstar cheering from a hospital bed. A family friend of Pulisic confirmed the authenticity of the post to ABC News.

Pulisic, 24, was helped off the field shortly after scoring a goal in the 38th minute of the match. Pulisic collided with Iranian goalie Alireza Beiranvand during the play and remained on the ground for several minutes. He did not return to the game.

He was taken to the hospital for scans on his abdomen, the team said.

Argentina, led by the legendary Lionel Messi, faces a critical match with Poland as it attempts to qualify for the knockout rounds Wednesday.

Group C is tightly packed with Poland standing at 4 points, Argentina at 3 points and underdog Saudi Arabia at 3 points. Mexico is at the bottom of the table with 1 point, but it does have a chance of making the next round.

If Poland or Argentina wins outright, it will qualify for the next round. If Saudi Arabia defeats Mexico, it will also improbably make it to the knockout stages. But who advances otherwise gets more complicated from there.

Mexico needs to defeat Saudi Arabia if it wants to advance, but they still would need to get a helpful result in the Poland-Argentina match (either a Poland win or a draw and advantageous goal differential). A draw in both matches would put Argentina and Saudi Arabia tied at 4 points and come down to goal differential as well. Poland would win the group.

Group D is more clear. France has already qualified for the next round, so they may take it easy against Tunisia. Tunisia would need to beat France, get a draw in Australia-Denmark and win out on goal differential.

The Aussies would advance with a win against Denmark. Denmark can only advance with a win, though it would need a better goal differential than Tunisia if the African country upsets France.

Here is Wednesday's schedule:

U.S. star forward Christian Pulisic said Thursday he is ready to return to his team for training and is still hoping to play in the team's knockout round game against the Netherlands on Saturday.

"I'm gonna go meet now with the team and the medical staff and make a decision on [training] today," Pulisic said at a press conference. "Just kind of see how I'm feeling. Take it day-by-day right now, but doing everything in my power to be able to be out there on the field Saturday."

Pulisic suffered a pelvic contusion when crashing into the Iranian goalkeeper after knocking in the eventual game-winning goal Tuesday. He was checked out by trainers and eventually returned to the pitch before being substituted out at halftime.

He was taken to the hospital for a brief stay before returning to the hotel to greet the team returning after the win.

He said in a post on social media from the hospital that he would play on Saturday, a sentiment he echoed to Fox reporter Jenny Taft Thursday morning when he told her he'd play. Officially, he is still listed as "day-to-day."

The U.S. faces the Netherlands in the round of 16 on Fox at 10 a.m. Saturday. A U.S. team hasn't advanced past the round of 16 since 2002 when they defeated Mexico in the first knockout game before losing to Germany in the quarterfinals.