Well, it seems the Daesh really out-played Gen Essam Zahreddine, CO of the 104th Brigade RGD and the regime's pocket in Dayr az-Zawr.
Through the entire day, Daesh was infiltrating various parts of regime's positions north of the city, inside the city, and south of it. They've captured even such places like al-Assad Hospital.
As usually, the regime hit back in force, supported by air strikes (supposedly: including those by Russians).
However, this afternoon the Daesh then launched a major attack from the south. At first fighting was then reported from al-Thardeh area in southern centre of the regime's pocket, and then the Daesh
claimed to have captured the oil field and hills south of Dayr az-Zawr, where it should have killed 25 regime troops.
Around 18.00hrs local time,
Daesh claimed to have cut off the Base 137 by reaching the 'Panorama Camp', which is roughly between the Base 137 and Dayr az-Zawr City.
Seems, they have captured Tel Kroum and then linked-up with northern prong of attack from the Saiqa Base.
All of this indicates the dire situation of the regime's garrison even before this offensive began: it lacked troops to cover its entire perimeter, and when Daesh distracted it and drew forces away through multiple infiltration attacks, the selected 'Schwerpunkt' was poorly defended.
The regime pocket should now be split in two and the last fuel supply to the air base cut off. Worse yet: the Daesh is in a position to turn east, link up with its positions inside the city, and thus cut the pocket in three.