Manchester United are waiting to discover if Javier Hernandez will be added to their injury list after the striker came off at half-time in Mexico’s 0-0 draw with Nigeria on Wednesday.
The 25-year-old forward withdrew from the friendly in Atlanta at the interval due to a knee problem, which could make Hernandez a doubt for Saturday’s game against West Bromwich Albion.
After the match, Mexico team doctor Jose Guadalupe Vazquez said he would wait on the MRI results, though was confident there was no ligament damage.
"It is a bruise, but we have to rule out any ligament strain," he said. "He only has pain and he doesn’t have a history of knee instability.
The bruise is in the middle part of the knee. We will have to wait to see whether it is a strain."
Results of medical tests run on Wednesday night were scheduled to be sent directly to United.
"Fortunately, Javier was able to walk without help, although he was in pain," coach Miguel Herrera said. "That should be good news because it must not be as serious as we initially thought. He wanted to play the second half but we couldn’t allow it. At that moment it was more important to avoid further injury."
Hernandez has been an unused substitute in each of United’s last three games and has not featured since the 2-2 draw against Fulham.
His last start came in the second leg of the Capital One Cup semifinal against Sunderland, when he scored, but he has only begun four Premier League games for David Moyes' side this season.
Hernandez had spoken of his frustration about his lack of first-team football for the Red Devils earlier this week, and is quoted by the Daily Mirror as saying: "I'm very eager to play as my club don't take me much into account. I hope I have the opportunity to play [for Mexico].
"When you are called up, you have to be thankful and if not called up, you have to keep working. I'm very happy and thankful with this call-up, like I was when I was called up for the first time."
Mexico coach Miguel Herrera revealed in February that Hernandez was frustrated with a lack of playing time at Old Trafford.
"[Hernandez] seemed well but he is a bit frustrated because he doesn't play, despite training well," he said. "And the truth is that when he does play, he makes a huge effort on the pitch.
"He is a bit frustrated because the current manager doesn't give him many chances, but he is committed and doing what he can to become a starter."