GLENDALE, Ariz.—We're roughly 24 hours before the United States men's national team takes the field against Mexico at University of Phoenix Stadium—the last match before American head coach Jurgen Klinsmann calls his pre-World Cup roster in May. "One last chance to show Jurgen up close what we're about, and we're excited about it," Landon Donovan, who will almost certainly be part of that squad, said before training on Tuesday afternoon.

Plenty of questions need to be answered as the 23-man roster takes shape. Here are five that should might just get answered on Wednesday against El Tri.

1. Will Julian Green make the roster?

This is the one getting the most press. Can the 18-year-old Bayern Munich product take a spot from one of the veterans who helped the U.S. qualify for Brazil?

At the very least, Green will get a chance to impress the coaching staff in a game situation. "Hopefully he gets tomorrow his first taste of what it means to play for the U.S. but also what it means to play in the biggest game you can play in the U.S. against our rival Mexico," Klinsmann said during a press conference.

Clint Dempsey, the captain who has been tasked with looking after the youngster, has been impressed. "He's a confident player," Dempsey said. "He's a good kid. Works hard. Has a good touch on the ball. He's not afraid to take people on. He makes good decisions. He's a player that you can see has a bright future."

He should play against Mexico and his presence adds another level of complexity to Klinsmann's decision. "Obviously, having Julian Green now available... adds another option for us," the coach said. "We want to bring him in and see where he fits in with the group without putting any pressure on the kid. This is obviously just a starting point of what we hope is a great career in the U.S. jersey." Smart money says he goes.

2. Who will play right back in Brazil?

Brad Evans isn't here. Neither is Geoff Cameron nor Fabian Johnson, who has been playing right back for Hoffenheim (and might be the U.S.'s best player at three positions). DeAndre Yedlin is here and so is Michael Parkhurst, who will play anywhere. "I don’t see too big of a difference between playing on the left side and the right side," he said. "I think that I can play there if need be and if Jurgen thinks I can help the team in that way then I have no problems playing on the left."

He'll probably start on the left against Mexico, and his versatility to play anywhere along the back line could very well get him to Brazil. Were I a betting man, I'd go with Evans—a combination of the Seattle Sounders player's skill and Klinsmann's stubbornness—but a special performance from Yedlin could put his name into consideration.

3. Do Besler and Gonzalez have starting roles locked up?

Klinsmann continues to trot out the center back duo as his No. 1 option. They have been solid but not spectacular, a bit too prone to losing focus for a split second. Obviously, that's not ideal, especially in a World Cup setting where the difference between advancing and, well, not is so small.

Mexico's quick attackers, like Alan Pulido, represent a chance for the pair to show their improvement in timing and communication. If they struggle, will Klinsmann make a change?

He has faith in Clarence Goodson. "They proved their game in Europe and now back in MLS," he said of the center back and Michael Parkhurst. "It's good to have them around. They make the entire squad better. They have proved it many times." That said, nothing short of an abject disaster will make the head coach rethink the two men in the middle.

4. Who will win the battle for the last forward slot?

No one has stepped up. The best performance came from Chris Wondolowski, who got both goals against South Korea after a strong January camp. The Americans have a serious lack of depth at the target forward position and the San Jose Earthquakes attacker can play that role. Though he remains a longshot, a second-straight excellent performance against a strong team will boost his case significantly. At this point, he's probably ahead of Terrence Boyd, right?

5. What about the backup midfield roles?

Maurice Edu badly wants back into the mix. He'll get a chance, although Kyle Beckerman is ahead of him and very nearly a lock to be on the plane. Of all the players in camp in Arizona, Edu might have the most at stake. He'll have a half to refresh Klinsmann's memory about what he can do, and make the case that his form has returned after last year's lost season. Will it be enough? We'll see (and his flexibility to play center back doesn't hurt, either).

Who would you bring to Brazil? You can make your own 23-man roster here with our new interactive tool.

Noah Davis is American Soccer Now's deputy editor. Follow him on Twitter at @NoahEDavis.