The statement in the headline may seem to be a bit of an overstatement. Iliman Ndiaye is always a key man for Everton, even with the presence of Jack Grealish and with Kiernan Dewsbury-Hall in the lineup.
But with the midfield further thinned by Dewsbury-Hall's absence due to a dubious yellow card accumulation, Everton will likely need to use Ndiaye in a way we haven't seen much since he joined the club: as an attacking central midfielder.
The Senegal international has been a versatile player throughout his career, featuring on both wings and as a central striker at times, but he's also been used more centrally in the midfield, most frequently during his time with Southampton.
Being in the middle allows Ndiaye to be a bit less predictable, as he can successfully carry the ball either to the right or left as the situation calls for it. While he can do this on the wing, along the right side he's shown a greater propensity to wrap around the right side and look for a cross, while on the left he's more prone to cut inside and look for the shot.
Against a defense as stingy as Crystal Palace, which has only allowed six goals across all competitions (11 matches), going back to the Community Shield match on August 10, the versatility that Ndiaye provides will be essential.
With KDH gone, Palace will be able to lock in even more on Grealish, a player who has received the bulk of the attention from opposing defenses, for good reason. He and Ndiaye can serve as a tandem left winger/no.10, swapping positions as the situation calls for it, and allowing either Thierno Barry or Beto to make runs forward into the box.
All of this, of course, will leave a hole on the right side that will need filling, which feels like an ideal opportunity for Tyler Dibling to feature, but David Moyes cannot lean on the youngster against such a quality group of defenders.
Instead, the manager can count on Ndiaye to change the game from a position he hasn't been used in much during his time with the Toffees so far.
While Dewsbury-Hall's suspension may be unjust, it could also be a blessing in disguise for Everton, as it will allow Moyes to take a look at what his lineup can look like without the midfielder. Moving forward, this may be the best thing for the club's health this season.