He has won back-to-back titles in North America and, overall, his performances on all surfaces since returning from injury imply he is back to his best, with the exception of that blip at Wimbledon.
And that first-round exit came against a man who will probably never play that well again. Rafa didn’t actually play so badly against Steve Darcis but, for a second time in consecutive years at Wimbledon, he came up against an inspired opponent.
Rafa has been the most consistent player this year, although we used to say that about Andy Murray before he learned how to win Grand Slams. He beat Novak Djokovic in Montreal but, other than that, he has not faced too many of the bigger players.
Can Rafa handle five sets on hard courts? His overall stamina and speed have not declined, but only he will be able to tell you if his knees can stand that kind of pressure. Sure he can do it on clay, but in New York? That is the only physical, technical or mental question that remains concerning Nadal now, and only he knows the answer.
And it is not a bad position to be in – Rafa hasn’t been an 'unknown quantity' in any aspect of his game since he was a teenager. Even this potential weakness can be used as a psychological weapon if, as I suspect, the knees are just fine.
For me, the biggest question is his level of opposition he has faced so far on hard courts. Apart from Djokovic, who has not been in his best form recently, Nadal has not been overly tested. Nadal’s lack of top-four opposition in this run would concern me more than his fitness. But his nine titles in 2013 speak for themselves.
That makes Nadal my joint-second favourite alongside Djokovic at Flushing Meadows. Nadal for his form, Djokovic for what he has done in the recent past.
I noticed some over-excited reports touting Rafa as clear favourite for the US following his antics at Cincinnati and Montreal, but that’s pushing it.
Murray is the favourite for the US Open because, over the past year, he has been the best player in the big championships – he has won two of four Majors, reached the final in Australia, and won the Olympics. He is the best big-match player at the moment, and appears to have 'cracked' his problem of winning Grand Slams.
Nothing I have seen since leads me to believe anything else – Murray will be the man to beat, but Rafa has a chance. A real chance.