Pune FC snapped ONGC's winning streak at the Ambedkar stadium with a solitary win in a 24th Round I-League clash in New Delhi on Sunday.
James Moga scored the all-important goal in added time of the first half. The South Sudanese striker volleyed home after being fed by Douhou Pierre who cut past two defenders to thread the pass.
Pune FC are now in third spot in the league standings with 40 points from 22 matches.
This was ONGC's first loss in their own den since Santosh Kashyap took over the reins last year in November. It leaves them on ninth spot with 30 points from 24 matches.
Pune FC coach Derrick Pererira was satisfied with the openings created by his team but felt they should have won by a bigger margin by utilising the chances that came their way.