The winger took a knock on the ankle during Sunday's Community Shield win over Chelsea.
And, while he was unable to train on Tuesday, or deemed fit enough to make the morning flight across the Irish Sea, Queiroz does not believe he is a doubt for the Premier League opener against Reading on Sunday.
"Cristiano didn't train yesterday and we didn't think it as wise for him to fly today," said Queiroz.
"But it is not a big problem and it is more a precautionary situation than anything else."
Queiroz also said he hoped the Premier League would quickly put the Carlos Tevez issue to bed by confirming his transfer to United.
But Sir Alex Ferguson's assistant virtually ruled out any chance of the striker being involved against Reading.
"Sometimes the administration side of things takes longer than you hope for," he said.
"At the moment, he is working hard on the training ground, so hopefully things will be sorted out soon and he can play his part next week."
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