West Ham striker Javier Hernandez was forced off in Mexico's entertaining 3-3 draw with Belgium on Friday night with a suspected hamstring injury.
In what will be worrying scenes for new Hammers manager David Moyes, Hernandez limped off after 51 minutes of the friendly in Brussels with an injury, and was replaced by Raul Jimenez.
The striker had won a penalty for Mexico earlier in the match, which ended 3-3, in what was his 100th appearance for his nation before he went down onto the pitch and appeared to be clutching his hamstring.
Mexico face Poland in another friendly game on Monday night, but it is unlikely that Hernandez will be risked.
Mexico boss Juan Carlos Osorio admitted after the match in Brussels that he didn't know how serious Hernandez's injury is.
"They're being observed and we don't know the seriousness of the injuries," he told reporters.
The news will also be a concern to Moyes, who was appointed as West Ham manager on Monday, with the Scotsman currently preparing his squad for the trip to Watford on Sunday 19 November.
The Hammers currently sit in 18th place in the Premier League standings following six losses, three draws and just two wins from their opening 11 matches this season.
