What happened: The latest injury involved the ACL and meniscus in McGregor's right knee. He underwent surgery after confirming both tears in July.
Why it matters: The setback halted his first fight in more than five years. It places another rehabilitation cycle between McGregor and the final bout on his UFC contract.
By the numbers: McGregor's ACL injuries occurred 13 years apart and affected opposite knees; the first came during his 2013 victory over Max Holloway.
What to watch: Watch for medical clearance and a timetable for McGregor to resume MMA training.