Nadal has played like 13 hours of tennis in the last 3 matches including more than 4,5 hours today. If a well rested Del Potro can't beat this Nadal then he's a total mug. He will never get a better chance again.
Depends on Rafa as well let’s be fair.
If Rafa is the one moving the ball around Delpo could feel it too. If Delpo comes out swinging making Rafa defend and do all the running, easy win for Delpo. At 32 he isn’t winning two gruelling five setters back to back.