Ronaldo's goal against the North Africans means he has now scored 85 global goals, more than any other European player in the history of football.
But they instantly eased off and offered little else in terms of attacking football for the rest of the match.
Morocco's Nordin Amrabat claims that referee Mark Geiger asked for Portugal defender Pepe's shirt following the Group B fixture on Wednesday.
Fernando Santos' side go into the clash as the heavy favourites after their performance against La Furia Roja, although the Portugal coach will want to guard against complacency.
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"We thought about what we did in the first game against Spain and we tried to rectify in training what we did not do so well, but there is no magic solution".
Iran have three points after pipping Morocco 1-0 in their opening group game. Arriving in Russian Federation with a point to prove having scored just three times overall in three previous tournaments, he doubled that tally in one game against Spain.
Morocco failed to convert their chances and are pointless and can not progress to the second round.
"There was no intensity in our game".
"As in the first game, we had a lot of chances and I won't criticise anyone".
"As with the game against Spain, after 10 to 15 minutes we lost control and possession".
Herve Renard's side dominated the ball, with Hakim Ziyach and Younes Belhanda both showing some nice flashes of quality, but they were unable to carve open any clear-cut chances, settling instead for a few hopeful crosses in the direction of Khalid Boutaib. "If you don't do that, then you get into trouble".