Portugal raised their game in the second half, with 34-year-old Ronaldo bagging three more goals with Bernardo Silva laying on two assists. Midfielder William Carvalho's close range shot completed the 5-1 rout in stoppage time.
It was Portugal's second consecutive qualifying victory after they had beaten Serbia 4-2 on Saturday. These wins have vaulted them to second place in the Group B standings, five points behind leaders Ukraine with one game in hand.
Portugal's next match is at home against Luxembourg on October 11.