The United States men's national soccer team kicked off their World Cup warm-up tour on the wrong foot with a 2-0 loss to Japan on Friday.

Given injuries to several key starters, this September camp will offer coach Gregg Berhalter a chance to evaluate players on the fringes. Not only did the loss shed some light on several issues across the pitch, but it also gave the Stars and Stripes the chance to face high-quality opposition.

It didn't turn out as planned, though.

The U.S. largely struggled against a high-octane, well-drilled Japanese side that overloaded the middle and stymied anything the Americans tried offensively.

Because of Japan's excellent defensive display, the USMNT were unable to get their attack going and ended the match with zero shots on target.

With injuries piling up, the lack of a true, consistent No. 9 and questions about the starting centre-back pairing, Berhalter and his staff will have a lot to think over before the team's next match versus Saudi Arabia on Tuesday.

Here are four takeaways from the USMNT's loss.

Berhalter has always had a distinct way of setting up his teams.

The USMNT have largely stuck with playing out of the back, using Tyler Adams as the deepest midfielder to progress the ball comfortably through the defensive and middle third of the field.

Against Japan, however, that tactic was found out rather quickly and wasn't as effective.

The Samurai Blue, despite having less possession, kept the USMNT on their heels and forced them to pass backward for most of the match with their high press and two defensive midfielders.

The centre-back pairing of Aaron Long and Walker Zimmerman in particular had a poor game in this regard. There were several moments when the duo was too slow on the ball and wasn't quick enough to get back into position when they lost it.

Once the ball was lost, the speedy Japanese front four of Junya Ito, Daizen Maeda, Daichi Kamada and Takefusa Kubo combined nicely in the space vacated to record several clean shots on goal.

Berhalter saw this problem and switched to a hybrid back three in the second half. That gave the USMNT a bit more control and allowed Sam Vines to get up the left flank and Brenden Aaronson tuck inside as central striker.

Though tactical changes were made, they fell flat. Japan comfortably saw the game out with Kaoru Mitoma's goal in the 88th minute.

Though the USMNT lost, they were without several important starters. Christian Pulisic, who was due to start, was pulled off the game-day roster with an injury he picked up in training.

Likewise, midfield standout Yunus Musah had to pull out a week ago because of a knock he picked up with Valencia.

In their place, Luca de la Torre and Giovanni Reyna started in the midfield and at left wing.

Both players are hugely talented and bring different profiles to the positions they play.

But it was evident that the progressive ball-carrying ability of Musah and the explosiveness of Pulisic were missing.

Luckily for the Americans, it is safe to say that Pulisic and Musah will recover in time to make the final World Cup roster.

Perhaps the biggest talking point heading into this slate of friendlies was the ongoing battle at centre-forward. It's long been talked about among media and fans alike, but with less than two months left until the World Cup, the discussion has an edge to it.

Jesús Ferreira started the match but was largely nonexistent. Not only did he miss a golden opportunity in the seventh minute, but he also had only 14 touches in the first half.

Josh Sargent came on in the second half, but, like Ferreira, didn't leave much of an impact with only 15 touches and zero shots.

If Ferreira and Sargent can't get the job done, maybe it's time to search elsewhere.

One of the most glaring omissions from this roster is Jordan Pefok. The 26-year-old has been in form for Union Berlin, who sit at the top of the Bundesliga with 17 points. Pefok has helped their ascent with three goals and two assists in six games.

Other options at the centre-forward spot could be Ricardo Pepi or Brandon Vazquez. Pepi's poor form aside, each player has shown they are capable of scoring and leading a line. Vazquez wasn't called up, so fans may have to wait a little longer for his inclusion.

Lastly, this game showed Matt Turner is the undisputed starter at goalkeeper.

The 28-year-old made some incredible saves that kept the USMNT in the match. He showed with his ability to quickly come off his line, his command around the penalty box and his shot-stopping skills that he can shake off rust and put in a solid performance.

He ended the match with three diving saves, three saves inside the box and 11 recoveries.

The question now is who will be the two other goalkeepers? Sean Johnson has been in good form for NYCFC and should definitely be in contention to be taken to Qatar.

There's also an argument for Ethan Horvath, who has been playing consistently for Luton Town. Zack Steffen, the former No. 1 for the USMNT, should also be in consideration.

This is the first World Cup in a long time wherein the United States hasn't had a definitive top option at goalkeeper.

It is uncharted territory for the Stars and Stripes, but, just like with the No. 9 competition, Berhalter should be prepared to take the player who is most in-form.

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