Javier Hernandez's former club doctor has warned Manchester United that the striker could have a long-term neurological condition.
Hernandez is currently sidelined for two weeks, after suffering a mild concussion when he was hit on the back of the head by a ball during a training session.
However, Rafael Ortega, the doctor at Hernandez's old club Chivas de Guadalajara, has revealed that the 23-year-old suffered from severe migraines as a teenager - and fears that both issues could be linked to a brain condition that would warrant further examination.
"I remember in his time as a youth player at Chivas he suffered from acute migraines," Ortega said. "Originally it manifested itself as a headache but afterwards the symptoms disappeared. We had some studies done on him but that was six years ago and he has done well since.
"I don't know if there is a connection between the two situations. I'm not up to date with the current situation, we would have to speak to a neurologist.
"I don't know if this will affect him in the future but I'm sure United will send him to a specialist and the situation will be resolved."
United manager Sir Alex Ferguson played down such concerns about Hernandez's long-term health, but admitted he would not be taking any chances with the player's recovery - especially as concussion sufferers tend to be more susceptible to repeat incidences of the injury.
"I'm not aware of that," Ferguson said, when told of Hernandez's previous history of migraines. "This is a straightforward concussion. He was hit on the top of the head with the ball in the early evening.
"When he was back at the hotel, taking his meal, he felt sick and he was sick. He had headaches, so we removed him to the hospital where he stayed in overnight.
"They did the MRI scans and that was all-clear. Concussion is something you don't want to happen but usually time heals that and we'll give Chicharito plenty of time. We won't be rushing him back. I'll only bring him back when the doctor tells me I can bring him back."