Newcastle and Stoke have both depended heavily on their key midfield men in recent weeks - the winner of that battle could dictate Saturday's result.
The Borussia Dortmund loanee has been central to wins over West Ham United and Swansea City, earning the club's player of the month award for August on Thursday.
But while Merino has instantly settled into the Premier League, his opponents have hardly been the most testing so far.
West Ham teenager Declan Rice endured a difficult afternoon at St James' Park, while Renato Sanches - making his Swansea debut - looked unfit and lost while Merino took control.
Against Stoke City on Saturday, Merino and Newcastle face a very different prospect.
Darren Fletcher has slotted into the Stoke midfield this season as an upgrade on Glenn Whelan and his experience and superior quality has shown.
The ex-Manchester United midfielder played a key role in Stoke's opener against his former club last weekend, but his defensive work is even more impressive.
After years of serving as Sir Alex Ferguson's trusted man for European nights, he will be well versed in dealing with talented stars like Merino.
Saturday's game could well be decided in that midfield zone as the two players go head-to-head.