First-timers Ghazi High School of Kabul also started with an impressive show in their maiden campaign
Although the final score tells a different story, it was a difficult encounter for the U-14 Nagaland team who became the first to enter the last four stage.
Their defence was put under pressure in the initial stages by the Manipur forwards and conceded the lead thanks to a fantastic strike by Alloudin.
They found their rhythm thereafter and it was a battle of equals although the Greenwood boys made better use of their chances with Nukhosa (25th min), Nokethozo (26th) and Tokavi (48th) finding the target, thus sealing their semifinal spot.
Meanwhile, coming from the war-torn Afghanistan, Kabul champions Ghazi High School are on their maiden trip to the Subroto Cup and they had a memorable debut with a 2-0 win over a clueless Government School, Fatehabad, Haryana.
The Afghans dominated the proceedings right from the kick-off, with good penetrative play down the flanks and clever combinations in midfield.
The Haryanvi lads produced some tenacious defending and robust tackles but Afghan captain Marouf (12th min) gave the visitors the lead. The local boys, despite a sturdy defence, could not prevent a second goal as Ali Bashid doubled the lead in the second half.
Although the Delhi schools are playing at their local grounds, they could not make their home advantage count and The Air Force School and Mamta Modern School finished their campaigns with disappointing results.
The former were handed a massive 15-0 thrashing by Government Chawngfianga Middle School, Kolasib, Mizoram who maintained the prevailing trend of one-sided contests with loads of goals. Striker Lalawnpuia led the way, equalling this year's record of most goals scored in a single match with seven strikes.