Ruiz told reporters: "Now, playing against England in the last game of the group will be special for me, too, after my time at Fulham.
"England will think it will not be easy to play against us. We have showed we can play with great character. They will know it will not be easy to beat us.
"It means so much for me to make it to the World Cup and now for Costa Rica to get into round two is a dream, too. England are under pressure. We accept they have more experience and a better league in England. But we know what we can do."
Costa Rica face England in their Group D match on Tuesday.