Ryan Giggs hailed a resilient Wales performance to hold Mexico to a goalless draw in California but was left fretting over an injury to Ashley Williams which saw the player taken to hospital.
Williams was forced off after stretching for the ball in the 17th minute and he was clearly in some discomfort as he left the field with a suspected rib injury.
“He’s gone to the hospital to get an X-ray,” Wales manager Giggs said of the Everton defender after the game.
“He’s gone to check that there’s no real damage, maybe just a cracked rib.
“They’re really painful. You breathe, you sneeze, you cough — it’s agony. Fingers crossed he’ll be OK, because we want him fit and back for pre-season.”
Aaron Ramsey took the armband following Williams' departure and the Arsenal man played the whole 90 minutes after shrugging off a first-half knock.
Wales were without Real Madrid forward Gareth Bale among others at the Rose Bowl in Pasadena.
They rode their luck at times and Wayne Hennessey made smart saves from Jesus Manuel Corona, Javier Aquino and Hector Herrera.
But an inexperienced Wales side held on to frustrate opponents heading to the World Cup in Russia next month.
“It’s a clean sheet against a very good team,” Giggs said. “There were also 80,000 Mexicans making it difficult for us, so I take that.
“The next part now is to show our quality, because we can do better in the final third.
“We were not rewarding the way that we were defending and the way that we had worked. So that’s the next step.”
Brentford's 20-year-old defender Chris Mepham excelled on his first start and Giggs gave opportunities to several other youngsters.
Connor Roberts, Declan John and David Brooks all came on as second-half substitutes, while there were also debuts for George Thomas and Matt Smith.
“I’ve learned that we’ve got quality in depth,” Giggs said. “We’ve young players who, if they’re given a chance, they’ll take it.
“That’s what I want. I want competitiveness between the squad, where we’re not just picking 11 or 12 players.
“We need to be ready if certain players can’t come in, we need those players to know how I want to work.
“We’ve got a lot out of the last couple of weeks and it ended with a magnificent test against a very good team.”