Newcastle United 0 West Ham United 2 - Newcastle United
Eddie Howe's side had gone into the international break in fine form, but that momentum was halted with a goal in each half from the Hammers.
As the two teams emerged from the tunnel there was a spectacular flag display celebrating Alexander Isak, who had scored in each of his previous four matches, and the Sweden star looked intent on adding to that tally from the first whistle.
In the second minute, Tino Livramento slid him in but the forward's effort from a difficult angle went wide, then four minutes later he dinked beautifully beyond Lukasz Fabiański but his celebrations were cut short by an offside flag, which was duly verified by VAR.
In the tenth minute, the visitors had the ball in the opposite net - Tomáš Souček powerfully heading home from Emerson's left-wing corner.
Joe Willock shot narrowly off target as the Magpies look to respond, but the Hammers continued to threaten on the break and, after a clever give-and-go with Jarrod Bowen, Spain international Carlos Soler's shot whistled just past Nick Pope's far post.
Sean Longstaff saw a header from Anthony Gordon's cross saved as the half-hour mark approached, then Lewis Hall drove at the West Ham defence but his low strike from the edge of the box went agonisingly wide.
Gordon was denied at close range by Fabiański in the 36th minute after the defensive lapse, then Joe Willock's follow-up was blocked.
Bowen fired over at the other end before United won possession through Bruno Guimarães, who brilliantly picked out Isak, but the striker half-volleyed wide.
In first-half stoppage time, a long-range snapshot from Bowen was well-fielded by Nick Pope as Newcastle went in behind at the break.
Harvey Barnes, who scored a brace from the bench in this fixture last term, replaced Willock at the interval and United started the second period on the front foot, with Gordon shooting just wide.
But the visitors struck a Hammer blow when Bowen found Aaron Wan-Bissaka, who drove beyond Pope from inside the area - his shot going in off the far post.
Pope then got down smartly to deny Bowen before the same player tested the United goalkeeper once more.
Fabian Schär - making his 200th appearance for the Magpies - fired well over from distance but the visitors almost added a third just after the hour-mark when Pope shovelled away Soler's free kick.
Isak headed wide from a hanging Livramento cross but with Newcastle struggling to find a way through, Eddie Howe brought on Callum Wilson for his first appearance of the season.
The number nine had scored 12 times in 14 games against West Ham for the Magpies and previous club Bournemouth - and had strong claims for a penalty when he went down under a clumsy challenge in the box from Konstantinos Mavropanos - but neither he nor his team-mates could help Newcastle find a route back into the game.
