Here on this, you are here on the forum, ah he the champion, don't compare, because of this injury, he missed a whole year past, and pain continued, so he and his manager know more than you.
If he was severely
injured, he wouldn't be playing against China on Davis Cup. Period. Would he be insane to put his whole career in jeopardy (because let's face it, at his age, a serious injury and he's done) if he was severely injured, just to play against freaking China on Davis Cup?
Common sense is required...
This is the typical "I'm playing Davis Cup on the other side of the world, therefore I'm not crazy enough to go play in the following week in some meaningless tournament two days later" injury.