At the age of 16 years and 361 days, the attacker became the Reds’ youngest scorer of all time by settling a topsy-turvy affair at St. James’ Park.
Ryan Gravenberch put the champions 1-0 up in the 35th minute ahead of the Magpies going down to 10 men on the stroke of half-time when Anthony Gordon was given a red card.
Hugo Ekitike made it 2-0 moments after the restart before the hosts clawed themselves back level through Bruno Guimaraes and William Osula.
But up stepped Premier League debutant Ngumoha off the bench to restore Liverpool’s lead and clinch the three points.
Team news
Gravenberch was one of two changes to the XI that started the opening-night victory over AFC Bournemouth, with Curtis Jones the other.
Dominik Szoboszlai began his night operating as a right-back.
Alisson, Van Dijk, Konate, Kerkez, Wirtz (Bradley, 80), Szoboszlai, Salah (Endo, 90+11), Jones (Ngumoha, 90+6), Gakpo (Elliott, 90+6), Ekitike (Chiesa, 80), Gravenberch.
Unused subs: Mamardashvili, Gomez, Leoni, Robertson.
First half
As fiery as the atmosphere and intensity was, clear-cut opportunities were hard to come by during the opening 45 minutes.
Florian Wirtz’s curler in the 13th minute, after Ekitike intercepted a slack pass out from the back, forced the first save from either goalkeeper.
At the other end, Anthony Elanga’s cut-back near the right touchline caused panic inside the Liverpool box, but he could not connect with his teammate Joelinton.
Gordon headed onto the roof of the net off Harvey Barnes’ cross and then stabbed straight at Alisson Becker from close range while under pressure from Szoboszlai.
Liverpool began to stem the attacks from the hosts with patient spells of possession and would take the lead during one of these encouraging periods.
Gravenberch needed no invitation to take aim at goal from distance when Cody Gakpo laid the ball off to him. The midfielder’s low strike flew through the legs of Guimaraes and took a kiss off the post en route to the back of the net, leaving Nick Pope rooted to his spot.
Newcastle’s hope of a recovery grew more difficult in added time with the dismissal of Gordon. His challenge on Virgil van Dijk was deemed to be serious foul play by the VAR, who recommended the overturning of the initial yellow-card decision.
Second half
The Reds flew out of the blocks and doubled their advantage 20 seconds after referee Simon Hooper blew his whistle.
Ekitike applied a lovely first-time finish, in off the post, from a Gakpo nudge just on the edge of the box.
But, in minute 57, we were back to where we began the second period when Guimaraes reached Tino Livramento’s delivery from out wide and planted a header into the bottom corner.
Even with their one-man advantage, it was set up to be a tense finale for Liverpool.
Newcastle’s pressure bore an equaliser two minutes before the end of the 90; a free-kick was punted upfield, flicked on by Dan Burn and then lifted over Alisson by Osula, who had not been on the pitch long.
There were 11 minutes of added-on time which both teams used to search for a winner.
It was to go the visitors’ way, however, when Szoboszlai skipped over Mohamed Salah’s low cross, allowing Ngumoha to make history and seal a dramatic win.
