The Chilean didn’t participate in Sunday’s 3-1 win over Ulsan Hyundai, which put the Rayados through to Thursday’s semifinal. He has now been confirmed out of action for a month, and returned to Mexico on Monday to begin treatment.
“Humberto is definitely out. The doctor gave us the diagnosis, and he’ll have to return for recovery,” said Monterrey coach Victor Manuel Vucetich. “He’s a great player and a key for us in attack. He’s a player that we’ll miss, but we’ve got the pieces to go on without him."
Midfielder Cesar de la Pena also returned to Mexico, due to an infection.
After falling in the quarterfinals of the Club World Cup last year, the Rayados swept through to the semis this year on the strength of Sunday’s win over the Asian champion.
The Mexicans are now in the process of preparing for a historic showdown with UEFA Champions League holder Chelsea, the winner of which goes on to the final.