@luke I think Sagan, just rode away.  Everyone went to sleep.  He rode.  Then Marcus Burghardt ( Bora-Hansgrove ) went to the front and soft pedalled for 1/2 min or so.  And suddenly Sagan had bridged over to the break, and the die was cast! 
I've rewatched it from 55 Km several times now!

It was a good race.  I was so excited wondering if Sagan and Dillier were going to get caught,