Al Muharraq of Bahrain survived many anxious moments before scoring a 1-0 victory over Mahindra United in the AFC Cup match at the Nehru stadium, in Margao, Goa, on Tuesday.
The all-important goal was scored in the ninth minute by Al Dakeel Abdulla.
Al Muharraq, who drew 1-1 with Mahindra at home, now have 10 points from four matches and lead the group.
The defeat was a setback for Mahindra United's hopes of making it to the quarter-finals. The Mumbai outfit is placed third in the group with three points from four matches.
The first half was confined to the midfield with the visitors having more of the ball as Mahindra United preferred to concentrate more on defence.
The visitors shot into the lead when a cross into the box from Abdulrahman Mahmood saw striker Al Dakheel Abdulla slam the ball in.
Al Dakheel Abdulla, who posed a constant threat to the home team with his nimble-footed runs, stretched keeper Sandip Nandy with a fierce shot and the custodian had to dive to his right to put the ball out of danger.
Mahindra came up with counter moves and had their best chance in the 24th minute but Surajit Bose, who found himself free inside the box after Yusif Yakubu played a forward pass, could only manage a weak shot straight into keeper Al Thani Ali Hassan's hands.
Leandson Dias missed a clear chance to double the lead for Al Muharraq after resumption when he drove the ball wide.
Mahindra brought on Steven Dias, Rauf Khan and Venkatesh in place of Surajit Bose, Gouramangi Singh and Samson Fernandes respectively, but their strikers were guilty of holding on to the ball inside the box, which allowed the rival defenders to dispossess them.
The second half belonged to Mahindra, who made most of their moves from the right but found keeper Ali Hasan a tough nut to crack as he made saves off Steven Dias and Sushanth Mathew.
The Indian side had a gilt-edged opportunity for an equaliser in the dying minutes but Yusif Yakubu failed to score with no one to beat. Even in stoppage time, Peter Siddiqui missed an open chance from handshaking distance, heading the ball over the bar.