But the 30-year-old is now back in training with the Scarlets and has his sights set on their RaboDirect PRO12 clash with Ulster on October 29 for his comeback game.
And despite Rees admitting it was a tough decision to take to sit out the World Cup, he is sure it was the right one as he looks to lead Scarlets on the European stage.
"I'm feeling really good at the moment," he said. "It was great to get the operation done and dusted and it feels good to be on the road to recovery.
"Of course it was a very difficult decision to have the operation. Being captain and ruling myself out of the World Cup was a huge decision but health comes first and in the end I couldn't bear the pain any more.
"We did everything we could to get me there but the operation was the only option in the end.
"Training has been going well and I have been stepping up from bike work into running and contact sessions and obviously I have been doing a lot of strength rehab work on the neck.
"The start of the Heineken Cup is something I have been targeting and hopefully I can get back playing at the end of October so I am ready to go for Europe."
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