This is the second biggest win of the I-League behind Dempo's 14-0 humiliation of Air india in 2010-11 where Martins had slotted home six.
In their first match under Dutch coach Eelco Schattorie, United began with a bang as Martins (2nd, 16th, 39th, 77th and 79th) scored at ease as the Bhaichung Bhutia owned side missed their star striker who was redcarded in their last outing.
Carlos Hernandez (22nd, 34th), Malswam Tulunga (71st), Mohammad Rafique (90+1st) came out firing on all cylinders while the hapless Sikkim outfit gave a bonus when Michael Rodrigues (90+3rd) netted an own goal to complete the goal glut.
The Sikkim outfit, this seasons qualifiers scored their only goal in the fifth minute through Nima Tamang.