Air India were without the services of star players Arjun Halapa, Shivendra Singh, Girish Pimple and Adrian D'Souza.
Western Railway took the lead when Manprit Singh converted a penalty corner in the 22nd minute, and extended it to 2-0 seven minutes later as Jaykaran deflected Sachin Kumar's hit.
The railway outfit added two more with Malak Singh's twin goals (54 and 58) to lead 4-0.
Air India managed to trim the margin with two late goals from Joga Singh's field effort in the 67th minute and a penalty corner conversion by Gaganpreet Singh in the final minute.
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Both teams were evenly poised in the first half with a goal each.
Binoy Bhengra (44 and 66) and Chandan Aind (46 and 69) scored a brace each in the second half, while Jonny Jasrotia (20 and 65) too chipped in with two goals. Tamil Nadu managed to pull one back through Deepak Bejawad in the 62nd minute.
Meanwhile, South Central Railway defeated Indian Navy 2-1 to keep alive their hopes of making the semi-finals from Group B.