Wow, that's a bit of a shock after the third set. Didn't expect him to put up much of a fight let alone win
Don't think he was struggling physically too much, only mentally. So the break helped him reset and sort it out. He was playing the better tennis the entire match really apart from those 20 minutes or so where he got the jitters. I was impressed by the amount of long rallies he won also, it's a good indicator of his fitness.
I know he's had a few injury problems but hopefully he wins this match (and a couple more) and moves on from there.
A few? He has a metal hip! And persistent groin injuries that may or may not be caused by said hip. No player has ever come back to play professional singles after such an injury.