Both aunt and nephew had laid claim to the legacy of Ms Jayalalithaa owing to Ms Sasikala's long association with Ms Jayalalithaa.
While the AIADMK's headquarters wore a deserted look, followers of Mr Dinakaran has started assembling outside his residence and arrangements are being made for a grand celebration. The results of the counting, which started at 8 am, are expected around mid-day.
The counting was halted briefly following a scuffle between the supporters of Mr Dhinakaran and the AIADMK.
The election is crucial for the AIADMK, which has inherited the legacy of Ms Jayalalithaa, its charismatic leader for several decades.

Followers of Mr Dinakaran has started assembling outside his residence and arrangements are being made for a grand celebration.
After Ms Jayalalithaa's death, Ms Sasikala had taken charge of the party. But her chief ministerial ambitions put her on a collision course with O Pannerselvam. OPS, as he is fondly known, was a regular stand-in for Jayalalithaa and had taken over the top job in the government.
Earlier this month, Mr Dhinakaran had lost his claim the AIADMK's two-leaves election symbol after the Election Commission recognised the merged AIADMK as the "real" party. The sidelined AIADMK leader contested with a pressure cooker as his election symbol.