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

The quality of his reserves is about to 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 Thursday night after a 2-1 quarterfinal victory against 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 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.

Kyle Beckerman is the likely candidate to step in for Jones. Graham Zusi would seem the likely replacement for Bedoya, but how the U.S. aligns to replace Wood may depend whether Gyasi 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.

COLOMBIA 0, PERU 0 (4-2 PK): David Ospina made a flying kick save in a shootout and Colombia reached the semifinals for the first time since 2004, at East Rutherford, New Jersey.