Two-time defending champion and local favourite Mary Ann, playing white, went into the endgame with a couple of extra pawns in a rook ending and then went on to convert her material advantage with clinical precision to beat G K Monnisha of Tamil Nadu.
Playing black Soumya (PSPB) exploited a pin against Michelle Catherina's king to create a passed pawn in a Sicilian defence to earn a full point.
Swati's draw meant that Mary Ann and Soumya joined the overnight leader as the trio shared the pole position with three points each.
Meanwhile, top seed Tania Sachdev's title hope got a severe blow after suffering a second successive defeat when the Air India girl went down to the youngest player of the meet, Ivana Furtado of Goa, the National Junior champion.
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Tania, who lost to Mary Ann yesterday, was off colour once in a Nimzo Indian defence to get into an inferior position playing black as the 14-year-old wrapped the issue on the 30th move.
Padmini Rout of Odisha, playing against her state-mate Kiran Manisha Mohanty (LIC) could make no headway in a rook and equal pawn ending and both players agreed to a draw in 40 moves.
Results (Round 4)
WGM Swati Ghate (LIC) (3) drew Bodda Pratyusha (AP) (2.5); WGM Padmini Rout (Odisha) (2.5) drew WGM Kiran Manisha Mohanty(LIC) (2); IM Nisha Mohta (PSPB) (1) lost to CM Bhakti Kulkarni (Goa) (2); WGM Mary Ann Gomes (W.B.) (3) bt WFM G.K. Monnisha (T.N.) (1); WIM Ivana Maria Furtado (Goa) (2) bt IM Tania Sachdev (AI) (1.5); Michelle Catherina (TN) (0.5) lost to WGM Soumya Swaminathan (PSPB) (3).