The former Manchester United man hurt himself attempting an extravagant overhead kick in the second half of the 2-2 draw against Barcelona and looked troubled by the joint thereafter.
But Madrid are confident he will be okay to play in Portugal's two World Cup qualifiers over the next eight days, against Russia on Friday and Northern Ireland a week on Tuesday.
A club statement read: "Cristiano Ronaldo will today [Monday] join the rest of the Portugal squad.
"The Real Madrid forward, who suffered a sprained left shoulder during the match against Barcelona, was examined at his home this morning by Real Madrid doctors, who have said that his injury is not serious and that he does not need to undergo more tests in a hospital.
"Real Madrid have already informed the Portuguese Football Federation that Cristiano Ronaldo will join their national team squad today in Obidos.
"Once there, the Whites' player will be kept under observation and will have no problem in playing on Friday in Moscow for Portugal against Russia in the World Cup 2014 qualifier."
Portugal have made a strong start to their Group F qualification programme, winning 2-1 in Luxembourg and 3-0 at home to Azerbaijan.