Ronaldo, who is 33, also scored all three goals for Portugal in their opening 3-3 draw against Spain and is the early front-runner for the Golden Boot award for most goals at the World Cup.
Morocco, who had a real go at the Luzhniki Stadium but failed to convert their chances, are pointless having also lost 1-0 to Iran and cannot progress to the second round.
Despite their battling display, Morocco will rue the unforgivable defending that made all their subsequent good work irrelevant.
They qualified for the finals without conceding a goal in six matches yet somehow opted against marking the most dangerous attacker at the tournament in the six yard box when Joao Moutinho swung in a cross from a short corner and Ronaldo duly buried the header.
It was his 85th international goal, taking him beyond Hungarian Ferenc Puskas’s European record, with only Iran’s Ali Daei ahead of him on 109 Portugal will play their last group game against Iran while Morocco face Spain, both on June 25.
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