Grealish has suffered a stress fracture in his foot, an injury which typically results in a three-month lay-off.

However, Grealish is likely going to require surgery, and Moyes suggested that will mean the 30-year-old will not be able to play again in the 2025-2026 campaign.

Ahead of Everton's trip to Brighton, Moyes said: "We believe he's probably going to need surgery. It's still not absolutely confirmed, but it probably rules him out for the rest of the season, yes.

"It's really disappointing for the player, and for the club, for all of us here. He’s a big character, great experience. We'll miss him. He's done a lot of really important things for us."

Grealish leads Everton in the Premier League this season for chances created, while he has also scored twice.

Asked if the injury will have an impact on whether the Toffees look to sign Grealish permanently in the summer, Moyes said: "It's far too early [to discuss what will happen]."

Moyes was also pressed on whether Grealish's injury will impact Everton's plans for the remainder of the January transfer window, which closes on Tuesday.

"We're out there looking," Moyes said. "We're not shying away from it. It's less likely than likely. You can find players in January, but we're seeing this window is becoming a really difficult one.

"People might [leave], but at the moment, we're not planning to [sell players]."

While Grealish's absence is a blow, Everton was able to welcome Kiernan Dewsbury-Hall back from injury in its 1-1 draw with Leeds United, while Jarrad Branthwaite came off the bench to make his first appearance of the season after recovering from a hamstring problem.

Michael Keane will also be able to play against Brighton, as he has now served a three-match suspension.

"We've got Michael Keane back," Moyes said.

"Jarrad played 45 minutes [against Leeds]. We've got Kiernan back. We're still waiting on Carlos Alcaraz and Tim Iroegbunam, but they're all getting much closer. Are they full fit, really up to speed? Maybe not, but they're not far off."

Branthwaite impressed on his comeback, completing 49 of 56 passes (88%), with 41 of those coming in Leeds' half.

"Jarrad was great," Moyes said of the centre-back. "He added much more calmness to us, his ability on the ball, his speed is really important as well.

"Keane's back as well, so we’ll enjoy having the competition and choose who is best for the game."