Has had surgery to correct a disc problem in his lower back. This went well and he should recover completely. His playing season is over now and let us hope he will be fully fit for the start of 2014 and do well in the first big major which will be the Australian Open.
It is a bit of a pity, I was hopeful that he might have a decent Asian tour, but if this helps him come back stronger next season then it's worth the break and it's clear that his back has been troubling him much of the year. Hope he recovers both physically from the surgery and mentally from the incredible high of winning Wimbledon this year.