In a clash of the bottom two sides in Group C, coincidentally both teams of Indian Super League (ISL) franchises, Chennaiyin FC reserves were handed a sixth consecutive defeat.
Gourav Mukhi (11') broke the deadlock early on, slotting the ball infront of an empty net. Goalkeeper Sayak Barai had done well to pull off a double save but Mukhi took advantage of the loose ball inside the box.
At the other end, Jamshedpur FC 'B' custodian Harpreet Singh kept shots from Prosenjit Chakraborty and B. Rohmingthanga at bay.
The visitors doubled their lead just before half-time through Harsha Parui (43'). He ran in behind the Chennaiyin defence and netted with 'keeper Sayak wrong-footed.
Bedashwor Singh, who was involved with the first team in the Super Cup was introduced after the change of ends. He showed some signs of brilliance but was failed by his strikers in the final third.
Mukhi had a chance to bring up his brace but could only hit the upright around the hour mark. The resolute Jamshedpur FC 'B' defence held on to earn their second victory of the campaign, coincidentally both coming against the Junior Machans.
The Jharkhand-based side are 5th with seven points in their kitty after six games. They next host Kolkata's Mohammedan Sporting at the JRD Tata Sports Complex on 21 April.
The Syed Sabir Pasha-coached side have four games to salvage some sort of pride. Their next assignment is at the same venue against Meghalaya's Langsning FC next weekend.