Neymar attempted to reassure fans that he is fine despite asking to be substituted during Santos' 2-0 win against Bragantino on Sunday.
Neymar struck his team's opener in the ninth minute with an angled free-kick to help Santos progress to the semifinals of the Paulista Championship.
However, the Brazil forward came off in the 76th minute with a thigh problem and had to receive treatment on the bench.
Santos manager Pedro Caixinha told a post-game news conference that Neymar will be evaluated on Wednesday when the team resumes training.
"Let's wait for him to be evaluated, let's hope everything is fine on Wednesday," he said.
Neymar, 33, wrote on Instagram: "I'm fine, I felt uncomfortable and thought it was better to spare myself! It's been a while since I played a game with this intensity ... I'm so happy to be getting back into my best physical shape! Thank you everyone for the messages."
Neymar made only seven appearances in over 18 months for Saudi side Al Hilal due to injuries before returning to his boyhood club Santos as a free agent in the winter transfer window.
Sunday's goal was Neymar's third in his last four games for Santos.
"He is a fantastic player," Caixinha said of the former Barcelona and Paris Saint-Germain star.
"His game rhythm is complete. Now, other cycles follow and he will complete to be the Neymar that we all stop to see. Our concern is not who we are going to face [in the semifinals of the Paulista Championship]. It's about getting ready to win. With Neymar, it's easier."
