Merino marked his first appearance since making his move from Borussia Dortmund to St James' Park permanent, in a deal worth £6.5m [The Daily Mail], by heading the winning goal against Crystal Palace to propel Rafael Benitez's side into the top seven.
The 21-year-old had initially joined on a season-long loan for a fee of £2.5m with a view to a long-term move but just eight games into that agreement he completed his permanent switch to the Premier League, signing a five-year contract in the process.
And Newcastle may come to value that investment in Merino's talent, with Elliot predicting both Barcelona and Real Madrid could soon be prowling around the player.
"Yes, I certainly see him in a bracket where clubs like that (Barcelona and Real Madrid) come into it, considering his age," said Elliot, who kept his third clean sheet of the season in the 1-0 win, according to The Independent. "It's only a matter of time before the very top clubs come looking at him, but we want to be a top club, too.
"We want him to stay here, we don't want to see any of our top players up for sale again. That is the mentality now. We bring them through, the manager is here. He's a fantastic signing from the manager and the scouting department and hopefully we'll just see him develop as a player and he fulfils all that potential at Newcastle.
"Micky has come on and done brilliantly, and it's great because it shows in every position you've got to perform. It's brilliant news he's signed permanently, great for the club that such a talented young player has committed himself.
"He's very, very good. You can see from his performances the talent. There's no reason why he can't go on to play at the very top. I certainly see no reason why not. At the moment he is our player and we have to make sure he takes us to the top. We've now got a brilliant bunch of midfielders and one of them is having to miss out every week."
The Under-19 European Championship winner with Spain began his professional career with Osasuna where he made 67 appearances across two season, before moving to Dortmund in 2016. But he failed to make an impression in Germany, earning just 11 outings, but he did enough to secure a move to Newcastle in the summer.
His move to the north east came following speculation linking him with a move to Athletic Bilbao. But Merino rejected the offer from the Basque club due to being unwilling to agree a long-term deal with another club after being regularly overlooked during the first season of his five-year agreement with Dortmund.
Instead, Merino moved to Newcastle on a season-long loan and though he was a substitute for the Premier League opener against Tottenham Hotspur, he has started every game since culminating in his decisive intervention against Palace five minutes from time.
Whether Barcelona or Real do indeed move to sign Merino remains to be seen. Barca are keen to identify a long-term replacement for captain Andres Iniesta despite agreeing a new deal with the Spain World Cup winner. Los Blancos meanwhile have recently prioritised signing young Spanish players with Theo Hernandez and Dani Ceballos the latest arrivals eligible to play for La Roja.