Ronaldo, who will be 37 by the time of the next World Cup, was unable to keep Portugal alive despite incessant pressure from his side in the dying stages of the match.
"It's time for me to step aside, to be honest with myself, to say there is a new generation rich with talent and it is time for them to take over".
Had there been better midfield options for Argentina - their crop of youngsters is extremely disappointing and one of the main reasons for their bad performances this Fifa World Cup 2018 - Mascherano would not have been the first name on the teamsheet.
The defeats also saw Ronaldo and Messi - widely considered among the greatest to have ever played the game - continued their embarrassing run of never having scored in the knockout stages of the World Cup.
Messi scored four goals and converted his spot-kick in a semi-final shootout against the Netherlands to lead Argentina to a first World Cup final in 24 years.
Messi did ride to their rescue with a superb opening goal to help squeeze past Nigeria 2-1 to set up a meeting with France.
"He is their leader, their captain".
"No team can win with one player alone", Portugal coach Fernando Santos said.
By that time, Ronaldo's situation at club level will be clearer after he raised doubts about his future with Real Madrid in the wake of their Champions League final win against Liverpool in May.
"We expect all players, former players, staff, fans and everyone to behave in a respectful manner, but having stars like Diego, [Carles] Puyol, [Javier] Zanetti, who have built up the fabric of football, and having them working with us on our goals is part of a much bigger picture".