Michael Tayo and Soccor Velho combined in the dying minutes to help Air India edge past Vasco 1-0 in the Group D opener of the 30th Federation Cup at Vidyasagar Krirangan, in Barasat on Friday.
When it seemed that the match would end goalless, an Uttam Singh corner did the trick for the airmen three minutes before the final whistle.
Tayo had positioned himself brilliantly to head the corner to Velho, who tapped the ball home from close range.
The Mumbai side thus avenged their 0-1 loss to Vasco, when they last met in the 11th round encounter of the I-League on November 30.
In another match, Mohun Bagan needed a brace from Jose Barreto to snuff out the challenge of Oil India 2-1.
Bimal Ghosh's Air India deserved to go ahead in the first half but for a refereeing error by O P Thakur.
Samson Singh sped into the box and unleashed a shot that kissed Vasco defender Vincent Pires's hand before hitting the bar in the 37th minute.
However, Thakur turned down the penalty appeal much to Air India's dismay.
Vasco had their chance of cornering glory in the first-half but the forward line failed to utilise whatever chances that came their way.
Uzbek striker Sherzod Nazarov had a couple of chances but could not defeat Air India goalkeeper Arup Debnath.
Barretto shines for Mohun Bagan
It was the green-and-maroons who took the lead as early as the fourth minute when India captain Baichung Bhutia found Lalkamal Bhowmick with a neat little backpass. The midfielder floated the ball to Barreto, who buried his header home.
Undeterred, Oil India pushed men forward for the equaliser and a spirited Durga Boro levelled the score in the 36th minute.
Taking advantage of a communication lapse between the Mohun Bagan defence and midfield, Durga let go a volley that gave an out of position Sangram Mukherjee no chance.
Stung by the reverse, Mohun Bagan coach Karim Bencherifa rung in two changes immediately after changeover, bringing in PC Lalwmpuiya for Shylo Malswamtuluanga and Ishfaq Ahmed in place of Lalkamal.
With Oil India's youngsters piling on the pressure, the Mohun Bagan players needed all their experience to hold fort.
It was once again Barreto who rescued Mohun Bagan. Following a corner from Marcos Pereira, Lalwmpuiya essayed the ball to Barreto, whose shot found Oil India defender Jyotish Basumatary's hand before going in.