But Ronaldo rubbished any talk that the tournament would be his last at international level, despite struggling for form this season at United.
“I hope to be a part of the national team for a few more years,” he said.
“I still have the motivation, and my ambition is high.
“My path here is not over. We have many quality youngsters. I will be at the World Cup, and I want to be at the European Championship, too.
“It has been a long road and I want to take the opportunity to say that the road is not over yet. You’ll still have to put up with me for a little while longer!”
Ronaldo had tried to force a move out of Old Trafford in the off-season but failed to find an appropriate suitor, having wanted to challenge for silverware and play in this season’s Champions League. He has also been linked with a lucrative move to Saudi Arabia.
The 37-year-old has 189 caps for Portugal, scoring a record 117 goals, and helping the side lift the Euro 2016 title.
Portugal are grouped with Uruguay, South Korea and Ghana at the 2022 World Cup.