Conor McGregor Undergoes ACL Surgery, Says It 'Went Excellent'

Conor McGregor is officially on the mend after injuring his ACL against Max Holloway ... The Notorious says he went under the knife this week, and the surgery was a success!

The UFC superstar posted the update fans were waiting for, declaring on Instagram ... “Surgery went excellent. I am confident.”

McGregor tore his ACL and meniscus in his right knee during his highly anticipated comeback fight at UFC 329 last month ... injuring the leg during the opening seconds of the scrap.

Referee Mike Beltran officially called the fight off after 69 seconds.

It's not the first time McGregor has suffered the same injury. Coincidentally, he injured his ACL in his first fight against Holloway in 2013.

Despite the serious damage, Conor still won that bout ... and was back fighting about 9 months later.

Question is, can he do it again ... or does 38-year-old McGregor heal more slowly than when he was 25?

If you listen to the former champ-champ, he's keeping a positive outlook, vowing to return to the Octagon next summer for the last fight on his UFC contract.