Ronaldo, though, was unwilling to make a hasty call on his international future on Monday (Tuesday AEST) and told reporters in the mixed zone that Spain enjoyed "a bit of luck" to score through substitute Merino in the dying moments of a match he felt could have swung either way.
"I'm sad to be leaving the World Cup like this," the Portuguese superstar said.
"I gave it my all. I did my best and I'm leaving with a clear conscience. It was my last World Cup, yes, but I'll now have time to reflect and be with my family. I won't be making any rash decisions."
The 41-year-old stopped short of confirming whether he had played his final game for Portugal, saying he did not want a personal decision to overshadow the team's campaign.
"I don't make decisions in the heat of the moment," he said.
Ronaldo, who helped Portugal win the 2016 European Championship plus the Nations League in 2019 and 2025, said he was proud of his contribution to the national team.
"I've won three titles for Portugal; before Cristiano Ronaldo, Portugal hadn't won a single title," the Al-Nassr forward said.
"The biggest title the national team has ever won was in 2016, the European Championship, which, to be honest, is just as significant to me as a World Cup."
Portugal's exit also came with Roberto Martinez's departure as manager, and Ronaldo offered warm words for the Spaniard.
"I loved working with him," he added.
"A great manager, a great human being and what he's done for Portugal is to be commended. I want to thank him and wish him every happiness.
"It's always sad to be knocked out of a major tournament. It's a World Cup. The team was really coming into its own. We played well, in my view. It could have gone either way, but that's football. We have to pick ourselves up and carry on.
"It's frustrating to go out like this, but we can hold our heads high."
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