Al Hilal coach Jorge Jesus fears Neymar "can no longer play at the level we are used to."
Neymar, 32, becomes a free agent at the end of the season and Jesus has claimed he is in the dark over the Brazil star's future plans.
Sources have told ESPN that Neymar is in preliminary talks with three MLS teams, including Chicago Fire, over a proposed move.
"I don't know anything about Neymar's future," Jesus said.
"I can't comment on things I don't know. The Saudi Pro League is one of the best leagues in the world. Neymar can no longer play at the level we are used to."
The Brazil international is recovering from a hamstring injury he picked up in November in just his second game back after being sidelined for a year following a torn ACL and meniscus in his left knee.
"When I created this team it was with [Aleksandar] Mitrovic and Neymar, before he had this injury that has left him out of the competition for 14 or 15 months," Jesus said.
"Things have become difficult for him, unfortunately. He is still under contract with Al Hilal and it may be up to him to decide his future. It depends on the club, on the administration.
"The only thing I know is that Neymar is not registered [in the Saudi Pro league]. Until Jan. 31 the [transfer] window is open. So I'm not going to speculate on things I don't know."
Neymar has scored one goal in seven appearances since he joined Al Hilal from Paris Saint-Germain in a league-record €90 million ($98.6m) transfer in August 2023.
The former Barcelona forward, who is Brazil's all-time leading scorer with 79 goals, was not registered to play in the Saudi Pro League for the first half of this season. He has played in the Asian Champions League.
Defending champions Al Hilal are top of the league, ahead of Al Ittihad on goal difference after 15 games played.
