JURGEN KLNSMANN'S U.S. men's national team defeated Ecuador 1-0 on Wednesday night in a tune-up friendly ahead of Copa America Centenario. It wasn’t all smooth sailing as the team struggled in the opening 45 minutes before the substitutes came in and transformed the game.

The upshot: This team might be ready for a changing of the guard. The second half was a dominant performance and some players made a case to supplant the established veterans. Will the coach see it that way? That remains to be seen. Here are four thoughts on the game.

1. Nagbe’s breakout performance

Darlington Nagbe was by far the best player on the field. By the end of the game, he completed all 33 of his passes and scored the 90th-minute winner. He was a huge reason why the team looked so much more cohesive in the second half after a dreary opening 45 minutes.

The significance of his performance cannot be overstated. Entering this tournament, it looked likely that Klinsmann was going to roll with the Michael Bradley/Jermaine Jones/Kyle Beckerman trio. Those three started against Ecuadore Wednesday and—predictably—it was a mess. When Nagbe came in, the U.S began to take control of the game. Yes, other players helped with this, but Nagbe was the biggest factor.

What was even more noteworthy is the chemistry between Bradley and Nagbe looked very strong. The two had a good understanding and their potential partnership could be immense.

Klinsmann has said that he wants to see new players make their case to overtake the veterans. It's hard to ask for anything more than what Nagbe gave Wednesday. This should give Klinsmann the confidence to bust up the Bradley/Beckerman/Jones trio with a superior alternative.

2. Father Time v. Dempsey/Jones/Beckerman

Klinsmann’s starting lineup was old and for the long-time trio of Clint Dempsey, Jermaine Jones, and Kyle Beckerman, it looked like Father Time might be closing in. While the three still might have good games left in them, a U.S. national team without them is coming into focus on the horizon.

When you have World Cup qualifiers with many days to prepare, that is one thing. But when you have full tournaments inside of a few weeks, it looks like it will be hard for these players to recoup. Jones, Dempsey, and Beckerman all played last weekend and looked tired today. For a tournament like the Copa America, the group stage will take place with only three or four days rest between each game. That can be hard for players in their mid-30s.

Heading into the Copa, Klinsmann might be forced to find ways to use these older players on a more limited basis.

3. Pulisic deserves serious minutes

Christian Pulisic gave a dynamic performance and made a huge impact in the game. He took on defenders and created chances and even played rugged defense. He helped open doors that just were not there before he arrived on the field.

His maturity was evident, as he didn’t look timid and he didn’t look cocky either. He just looked like he belonged and knew what to do when he was on the field. He played to the level he he has displayed at Borussia Dortmund.

At some point Pulisic will struggle and hit growing pains. But that is a discussion for another day. Right now he might just start for this team at Copa America Centenario. If not, he should be a very useful offensive weapon off the bench.

4. Brooks poised to claim starting spot

Another good piece of news for Klinsmann is that the central defense picture came into focus as John Brooks played a solid match against Ecuador. He was by far the best American player on the field in the first 45 minutes and helped keep the U.S. in the game at a time when Ecuador had the upper hand.

Brooks has always had the talent but translating his club performance to the national team has been a struggle. This performance against Ecuador was perhaps his best defensive effort of his international career. If Klinsmann wanted Brooks to make his case to start, this was it. He broke up plays, distributed well, and most importantly did not make any glaring errors. He was focused and dialed in from the start.

My guess is that Brooks and Geoff Cameron start in central defense against Colombia on June 3.