Crystal Palace manager Patrick Vieira bemoaned Chelsea's decision to not allow loanee Conor Gallagher to feature in the FA Cup semi-final, claiming the midfielder will be "the only one who will lose".

Gallagher moved on a season-long loan from Chelsea to Selhurst Park at the start of the season and the midfielder has starred for the Eagles, who made the last four of the FA Cup with a 4-0 win over Everton.

The 22-year-old's performances also earned him his England debut in November and have led to suggestions he could fill a midfield void for Thomas Tuchel's side next campaign with N'Golo Kante, Mateo Kovacic and Jorginho not getting any younger.

But Chelsea have refused Palace's request for special dispensation to allow Gallagher to play against his parent club in the FA Cup on April 17, with FA rules preventing loanees from featuring against the side they are contracted to.

Vieira was left bemused by the decision as he insisted Gallagher would be the only player punished by the refusal.

"It's not the best rule because the only one who will lose is Conor," the Frenchman said.

"There's a semi-final, it's a really exciting game about how you will manage yourself and prepare yourself to play that game, then there's playing that kind of game and the importance of it.

"It's an experience the player is missing and I'm disappointed for him. He has played all the games so far and if there's somebody who deserves to be in the semi-final, it's him because of his performances, so I'm disappointed he won't be able to play.

"The decision for Chelsea to send him on loan is to play these kinds of games. We have as a group an opportunity to play an important game and that game would have given him more confidence and belief. We could lose but for him to have been on the field is what he needs to keep developing himself.

"Since he has been with us, he has been fantastic and for him not to have a chance to get involved in that game, it is something frustrating for his development.

"I feel for him because he wanted to play in that game –every player would want to play in that game."

Vieira also believes the impact of the FA Cup last-four draw has been clear to see on Gallagher in training.

"The next day in training he was affected by that," he continued. "He knew straight away that it was a game that he would not have the chance to get involved in. We feel for him.

"He put his head back into training straight away. It will be more difficult when we enter the week of the game.

"It will be challenging for him, looking at the team, preparing himself and him not getting involved. That will be challenging for him."