Djokovic hasn't retired from a match for a while, this may be the one to do as it looks like he's suffering and playing so soon after a hit to a head it may be the sensible thing to do.
Why do fedaltards always know, without a shadow of a doubt, that Novak would trade slams for something, whether it's their love, or Olympics, or whatever?
And mind you, it's always slams; not one, but always multiple.