Las Palmas - Wolves full-back Jonny Castro suffered a potentially serious knee ligament injury while playing for Spain in a friendly against Bosnia on Sunday.
The national team's medical staff said he would undergo further tests to determine the severity of the injury.
The 24-year-old had to be replaced early in the second half in Las Palmas after colliding with an opponent, before leaving the stadium on crutches.
Jonny has impressed since joining Wolves on a season-long loan from Atletico Madrid in July, starting all 12 Premier League matches and scoring one goal.
He made his international debut for Spain last month and Sunday's game was only his second start for the 2010 world champions.
