When Jurgen Klinsmann started experimenting with his roster following the 2014 World Cup, the U.S. coach did it with the hope of building more depth for the next four-year cycle.

The quality of his reserves is about the get tested in a big way after the United States advanced to the semifinals of the Copa America for just the second time. The U.S. will be missing three suspended starters: midfielders Jermaine Jones and Alejandro Bedoya, and forward Bobby Wood.

"Our program is maturing. Our players are maturing. They are learning with every game that we can play in this type of environment," Klinsmann said after Thursday's 2-1 quarterfinal win over Ecuador. "This is what we hoped for after breaking through in Brazil after getting out of the group of death. Hopefully we can find a couple of youngsters coming and keep the older ones on board and keep them going, push them. ... We've brought a few youngsters along the way the last few years and they've made a huge step forward tonight."

The U.S. will play the winner of Saturday night's quarterfinal between top-ranked Argentina and Venezuela, with the semifinal set for Tuesday in Houston.

Jones was sent off with a red card early in the second half against Ecuador, and forward Bobby Wood and winger Alejandro Bedoya both picked up their second yellow cards of the tournament, The U.S. Soccer Federation has appealed Jones' red and Wood's second yellow.

"It's tough," Bedoya said. "But we knew going into this game that some of us were on yellow cards. We all spoke before and if we miss the semis, who cares? The most important thing was getting to the semis and we did that."

Klinsmann made two changes before the quarterfinal against Ecuador due to DeAndre Yedlin's red card, inserting Matt Besler at left back and moving Fabian Johnson to right back.

But that little shift Klinsmann made for the quarterfinals was simple compared to significant moves he'll need to make for the semifinal, especially if it ends up being against Argentina and five-time FIFA Player of the Year Lionel Messi.

"The coaching staff, they always do an amazing job of scouting our opponents and utilizing the players that we have," said Gyasi Zardes, who scored against Ecuador to give the U.S. a 2-0 lead.

Kyle Beckerman is the likely candidate to step in for Jones. Beckerman has 56 career appearances for the national team and not as creative on the offensive end as Jones, has more of a defensive mentality that could be critical if Argentina is the opponent. Another possible option is Darlington Nagbe. If Klinsmann decides he needs a bit more offense from the position, the 25-year-old could step into a role he assumes for his club in Portland and keep Beckerman a defensive option off the bench later in the match.

Graham Zusi would seem the likely replacement for Bedoya, but how the U.S. aligns its offensive attack to replace Wood may depend whether Zardes is pushed further up field. If Zardes stays in the midfield, Klinsmann could turn to Chris Wondolowski to pair with Clint Dempsey up front. Or he could start Zardes higher up and insert 17-year-old Christian Pulisic.

The 23-year-old Wood was exceptional against Ecuador at making runs in behind the defense and holding possession in the attacking end. His ability to keep control of the ball as defenders closed led to both American goals against Ecuador.

With Jozy Altidore missing the tournament due to a hamstring injury, Wood has proven he can step in as a holding forward and allow others like Dempsey to be creators around him.

"We're confident. We're confident that we can keep up with any team," Wood said.