On the day he formally became a Chelsea player - the day he ended his ties with Ajax - Ziyech took to social media. There was no big farewell post - he'd already taken care of that. No cliched pic of the Amsterdam Arena in the distance. It was simply a snap of him in the gym with his personal trainer. But there was nothing simple about the message.
Ziyech is well across the debate of how he'll handle the rigours of the Premier League. He knows good friend and former Ajax teammate Anwar El Ghazi has been hammered by Dutch pundits for suggesting he'll need to 'hit the gym' if he wants to succeed in England. And with the July 1 snap, Ziyech showed which side of the table he falls on in this dispute.
"Ziyech has his qualities, he does not like his physical condition," has reasoned Aston Villa midfielder El Ghazi. "Why is he so good? Because he is so agile, because he can move well, because he is so thin.
"You have to think about your core, doing abs, pulling them up ... It doesn't make you a bodybuilder.
"The gym doesn't just mean pumping and pumping. I know Ziyech and he just has to do his exercises in the gym. You have to think about your muscles."
In his previous 134 posts to Instagram, Ziyech had never shown himself working in the gym. Friends. Teammates. They'll admit publicly that Ziyech avoids the place like the plague. There's no coincidence with this one. On his first day as a Chelsea player, he's let us all know how he spent it.
Ziyech knows this is a massive step up. Bigger than Twente to Ajax. Even bigger than Dronten to Heerenveen. A handful of impressive performances in the Champions League is no gauge to how he'll perform in the Premier League. The Morocco international knows it'll be about consistency. It's what he's discussed with Frank Lampard. The Chelsea manager will surely have had an influence on where Ziyech spent July 1. A tailored progamme already put together and pinned to the fridge at home.
"We will formulate a plan for them that will be slightly different individually," commented Lampard last week on the imminent arrivals of Ziyech and fellow new recruit Timo Werner. "And I will decide in the meantime how it looks at the training ground - whether that means mixing with the squad or whether it means doing some physical work in the short-term for themselves."
Ziyech does need to be stronger to make it in England. Football-wise, the Premier League is as good as anything in the world. But it's the physical side of the game. The attrition. That's what makes the league so unique. If Ziyech is to translate what he's achieved in Holland to the biggest stages in England, he needs to perform and play at a consistently high level. Something he can only do by getting physically stronger.
And it's consistency that Lampard is desperately seeking as the top four battle reaches it's critical conclusion. Defeat to West Ham United this week was a blow. A heavy blow. And while he didn't spell it out clearly, Lampard's post-match reaction offered enough to explain why his spending won't end with Ziyech and Werner.
"If you don't get details right in big games, you're going to drop points," stated Lampard after the 3-2 reverse. "I think at times we have played really well this season. As a group we need to find more consistency."
Bar very rare cases, consistency comes with experience. If the arrivals of Ziyech and Werner weren't enough, then Lampard's comments should have completed the convincing. As talented as this group of kids are, the manager doesn't believe they can get him to where he wants to go - at least not on their own: "It is why we are fighting for top four not one or two, because we don't get things right as much as the big boys do".
Lampard will be hoping Ziyech - with a couple of extra kilos on his frame - can help bridge that top-two gap. It may mean Mason Mount taking a backseat. Even Ruben Loftus-Cheek. Though it will all get down to consistency.
Ziyech knows this. It's why he's broken a habit of a lifetime. "A special player", has declared Louis van Gaal. Or as local commentator Jan Roelfs says "When I make a list of Ajax players, I think of Johan Cruyff, Marco van Basten, Dennis Bergkamp and Hakim Ziyech, in that order. I really think he is close to that as a stylist".
But Chelsea supporters - and fans in general - are only going to see that "style" if Ziyech's body can handle the Premier League's physical demands. Demands which, by this week's social media activity, he's taking seriously.
“Do you really think Hakim Ziyech will hang on those weights for an hour and a half four times a week?" so says the former Brighton defender Hans Kraay Jr, "No, he will not do that..."
Won't he? Now a Chelsea player, Ziyech is already proving such claims wrong. And if he continues just as he's started, those detractors convinced his game doesn't suit the Premier League will also be forced to sing a different tune.