The lone Puducherry seat will witness a direct fight between the Congress and its splinter group, the NR Congress led by former chief minister N R Rangasamy, in the Lok Sabha elections due in May.
The NR Congress will fight the elections as part of the AIADMK-PMK-BJP alliance in the Union Territory.
AIADMK announced the electoral arrangement after Rangasamy met Chief Minister Edappadi K Palaniswami and sought Puducherry seat.
With the Congress getting Puducherry in the DMK alliance, the seat will witness a direct fight between rivals.
In the direct contest in 2014, NR Congress leader R Radhakrishnan had trounced Congress' V Narayanasamy, the incumbent chief minister, with support from the BJP.
Rangasamy launched his own party in 2011 after he was forced out of chief minister's post in 2008 by the Congress.
With Narayanasamy firmly in his saddle, the Congress is considering fielding its leader V Vaithilingam, current speaker and a former chief minister, from the Puducherry Lok Sabha seat.