A goal in each half by Sunil Chetri helped JCT beat Dempo 3-2 in a 13th round match of the National Football league at Nehru stadium in Margao on Thursday.
The defeat is a setback for Dempo who are eyeing the title as they have 23 points from 13 matches.
JCT now have19 points from 13 matches.
JCT, who led 1-0 at the half-time, scored through Sunil Chetri (30th, 56th) and Sukhwinder Singh (78th). Anthony Pereira (60th) and Roberto Silva (84th) reduced the margin for Dempo.
Dempo had an early chance to score through combined effort of Ranty Martins and Peter Carvalho. Carvalho's shot from inside the box was fisted over for an abrotive corner in the eighth minute.
A minute later, Sunil Chetri, who was later adjudged the man of the match, had an opportunity to score but the striker ended heading straight to Dempo custodian Satish Kumar.
Thereafter, play was confined to midfield for a brief period with JCT taking the lead in the 30th minute.