The 32-year-old lasted just 26 minutes as a second-half substitute before limping off with an apparent right hamstring strain in Monday's 3-0 AFC Champions League Elite win over Esteghlal.
Neymar, who moved to Saudi Arabia from Paris Saint-Germain in a lucrative deal in 2023, was out for more than a year until last month following right knee surgery.
Al Hilal coach Jorge Jesus said earlier this week that Neymar would miss at least two weeks' training following his latest injury setback.
"He will undergo a treatment and rehabilitation program that will last from four to six weeks," Al Hilal said on social media.
Al Hilal, the reigning Saudi champions, have not registered Neymar for the current Saudi Pro League season, which began last month.
But the former Barcelona player, with a reported salary of about 100 million euros ($112 million) a year, is listed to play in the AFC Champions League Elite, Asia's biggest club tournament.
November 6, 2024