The Real Madrid full-back pulled up in the second half after stretching to keep a ball in play, and he has delivered an honest assessment of his chances of recovery.
He told AS: "I honestly think the World Cup is over for me. I'm sure it's a serious injury, although I hope I'm wrong. Sadly, these things happen in this job.
"It's a sad day, one of the saddest of my life but it's only the first game and despite the result, we could still get through to the next round."
Paulo Bento's side play USA on Sunday.