Hope the two days' rest has worked to his benefit!
I also think keeping fit and healthy should be his top priority, but at the same time he (and all the up and comers on the main tour) needs to learn how tough it is to play week in, week out on the ATP tour. I don't want him to push himself too hard and get seriously injured, but if he can manage small niggles here and there that's good for him as well, because that's what all the pros are doing.
Remember, Del Potro used to retire a lot until his breakthrough this summer. Young players are also prone to cramping than experienced players. I think Kei is now learning how to negotiate his fitness in the busy tour schedule, and I hope he's always in good hands when he has a physical problem!
Good luck against Hrbaty today! The Slovak plays his best indoors, and he seems to be playing well, but if Kei has got over the knee problem and cold, then there's no reason why Kei should lose to the guy. Go Kei!!
(I may not be able to follow the livescore today but I wish him the very best!