From Djokovic's perspective it's at 6-3, 3-6.
From del Potro's perspective it's at 3-6, 6-3.
The extra day may be a double edge sword for del Potro. On the one hand it gives his surgically repaired right wrist and recent bad hip some extra rest but on the other hand it kills the momentum he gained by winning the second set rather easily. Whatever dent he exposed in Djokovic's armor in the second set needs to be carried over into the third set tomorrow.
For Djokovic he gets a chance to study the film and rectify whatever mistakes he made in the second set and come tomorrow with the mentality that this is a semifinals match (and not a third round match) because that's the type of player he's playing-- a former World No. 4, a former French Open semifinalist and the 2009 U.S. Open champion, who seems to be fully healthy again.
So tomorrow the battle resumes as a best of three.