McKennie had been nursing a quad injury over the past few weeks, but with club side Juventus and the U.S. working together to monitor the midfielder's progress, he has been steadily building up his fitness.
"The week has gone good," McKennie said. "Obviously in my personal position or how I'm doing or how I am in terms of recovery, I came in good, I came in at a pace that was controlled.
"Juventus and the national team, they were both working together to make sure that I'm 100 percent fit here. So I came in, did a couple days of just maintaining and keep it under control. We played the friendly the other day, and I felt good. I felt ready to go, and that's where I'm at."
Similarly, Dest was suffering from muscle fatigue, and had even once trained indoors apart from his U.S. teammates since arriving in Qatar.
"I'm feeling good," he said. "Of course, after the last game, I had a little bit of fatigue. Right now, it's going well. I'm ready to play."
Details have emerged from Thursday's scrimmage against Al-Gharafa SC -- though publicly the U.S. are still saying it was a "training exercise" -- with the Qatari club divulging that the U.S. prevailed 6-0.
"It was a great scrimmage. We got a lot out of it, defensively, offensively," defender Aaron Long said. "The finishing was great. Obviously, we had a couple of goals in there to get the guys confident in front of the net."
Now the focus is firmly on Wales, and how the U.S. will try to break down what will likely be a five-man backline in a bid to get off to a fast start in the tournament.
"As a team, as a group, we always want to just focus game by game," McKennie said. "So of course with Wales being the first one, there's no way that we're going to look past them or anything because we know they're a strong team.
"We know that it's going to be a hard game. But we definitely want to win the first game, to come out with three points. [It's been] just three, four years of just working up to this moment, I think all the guys are ready to go, and the staff is ready to go and put a game plan together. So hopeful we execute that."