Fresh from their derby victory Sunday, East Bengal started in an inspiring fashion with Edeh Chidi's 32nd minute goal but Singh headed in the equaliser in the 59th minute dodging burly Uga Okpara to take some points off their fancied local opponents.
United SC now have 16 points from 10 matches, while East Bengal have 11 from seven outings.
For newly appointed East Bengal coach Armando Colaco who started his stint with a fine win over bitter foes Mohun Bagan the draw may be demoralising as they hit the road for five consecutive away fixtures.
The red-and-gold brigade clearly looked more penetrating in the first half.
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United SC too benefitted from a dubious decision when a penalty was ruled out with Debnath bringing down Chidi inside the box.
But moments later the Nigerian fired in the lead utilising a Saumik Dey header.
East Bengal was also wasteful after the changeover with Ryuji Sueoka missed an easy chance to double the lead.
But United SC were in no mood to give up with Dhanachandra scoring the all important goal beating the tall Okpara, in one rare lapse by the burly EB defender.