Prameshwari Devi (2) and S Rina Roy Devi (1) scored for Manipur, who have not conceded a single goal in three matches and scored 25 till now in the tournament.
Sikkim 'Red' and Assam, having three points apiece, will play against each other tomorrow in a crucial tie that will decide the second semifinalist from Group A, after Manipur.
Tamil Nadu and West Bengal shared one point each after they played out a 1-1 draw. Tamil Nadu established 1-0 lead in the 46th minute from a goal by Angal Adolfes.
Soma Seal struck the equaliser in the 69th minute.