“Mikel is incredible,” Spain boss Luis de la Fuente said after the quarter-final win.
“He has many qualities. He is a player that across the whole World Cup could have played in whatever team and done great.
“For us he is the standard of this idea, of this model. It is a pleasure to have him, and others but especially him. We know that without fail he is always there.”
Always there he may be, but Merino himself feared he would not be fit enough to play at this World Cup.
“The fact of being here a few months ago was unthinkable,” Merino said after the Portugal win.
“Now I am, as I said before, at the highest point, enjoying one of the happiest moments of my career.
“Now I remember all those bad moments, all the people who have supported me, all the people who have pushed me when even I sometimes found it difficult to believe I could be here.”
Merino’s heroics will be a familiar sight for Arsenal fans, with the 30-year-old having done similar at the Gunners.
Traditionally a midfielder, his height has seen him utilised as a striker by Arsenal boss Mikel Arteta, and the first time he was used in such a role was when he memorably came off the bench to score twice against Leicester in a 2-0 win in February last year.
“Merino is just one of those players who arrives at the right time, at the right moment in big games,” former England striker Wayne Rooney said on Match of the Day.
De la Fuente added: “He can be the best striker and the best midfielder because of his understanding of the game. He interprets the game perfectly.
“He is committed, he is generous, he is happy to do the work.”