Valencia put host nation Qatar to the sword with both goals as Ecuador run out 2-0 winners in this year's FIFA Word Cup opener at the Al Bayt Stadium.
Former Everton and West Ham United striker Valencia, who now plays for Fenerbahce in Turkey, first had a third minute header ruled out for offside by the Video Assistant Referee.
But the 33-year-old did not have to wait too long for his moment of redemption as he neatly tucked away a penalty in the 16th minute after a foul from Qatar goalkeeper Saad Al Sheeb.
Just after the half hour mark, Valencia again headed in Angelo Preciado's cross to hand the South Americans a commanding lead.
Valencia suffered a knee injury late in the first half but returned for the second period before getting substituted 15 minutes from time.
But Alfaro insists Valencia will be ready to face Netherlands in Ecuador's second group game on Friday.
"He is the all-time top scorer for Ecuador, he is going through tough times, he was questioned at times in Ecuador," said Alfaro.
"He managed to score, which means a lot to him. Four or five players took a few blows, but nothing serious.
"Enner will play against the Netherlands, there is no doubt about that."
Valencia now has five World Cup goals to his name after netting three in the group stages at Brazil 2014.
