"He's coming along really well," Lynch said on the Tolbert, Krueger, & Brooks podcast. "I think, truly, Week 1, that's, I don't know, 50-50. But it's going to be touch and go as to whether he makes it."
Bosa is two weeks removed from suffering an ankle injury during training camp. San Francisco ruled him out for the entire preseason due to the ailment.
The defensive end shed his walking boot Aug. 14.
The 49ers are hoping Bosa can help ignite their pass rush, which ranked tied for 22nd in sacks last year.