Mohammed Kudus scored his first West Ham goal as the Europa Conference League holders came from behind to beat Serbian side Backa Topola in the opening game of their Europa League group campaign.
The Hammers enjoyed one of the finest nights in their history back in June when they beat Fiorentina in Prague to win the Conference League for a first European trophy since 1965.
But they were given an early taste of the challenge facing them following their elevation to the continent's second-tier competition.
The visitors, also known as TSC, were disciplined, determined and handed the chance of a famous win by an awful error from Angelo Ogbonna that allowed Petar Stanic to rob him of possession before running on to finish past Lukasz Fabianski.
But West Ham know the score now on these European nights and, despite a wobble after conceding they dusted themselves down, made changes and dragged their way to victory.
Kudus was in the mix for the leveller, his presence at the back post enough to force Nemanja Petrovic to bundle Said Benrahma's cross into his own net.
The summer signing from Ajax did get his goal soon after, nodding a James Ward-Prowse corner through a crowd and into the far corner.
The home side ensured a stress-free close to the game when substitute Tomas Soucek headed home from another Ward-Prowse corner eight minutes from time.
Before Thursday's game, West Ham boss David Moyes urged his side to create more "magical moments" to match those experienced over the last two seasons - and most prominently in the 2022-23 campaign.
With all due respect to TSC, the Scot is unlikely to place a hard-fought home victory over them - with a largely second-string side - in the same bracket as that win over Fiorentina, even if the Serbians do currently top their domestic league.
However, Moyes is pragmatic enough to know it cannot all be confetti cannons and champagne.
He will be very pleased with the way his team were able to wrestle back control of the game and take the points after first-half frustration and the wobble following Ogbonna's error.
The Hammers boss has to take some responsibility for the lack of coherence and cutting edge as a result of the nine changes made from his starting XI from the weekend.
The intent was clearly to rest key men, but what it resulted in was a display lacking what was required to open up an opponent prioritising a point and packing their own box to that end.
The hosts dominated possession and created chances from which they could have led - a Ward-Prowse free-kick deflected over the bar, Thilo Kehrer's saved effort and Kudus having an effort touched wide.
But TSC's growing belief became visible before the break with a late dart on the Hammers goal that resulted in Nemanja Stojic's header from a corner that clipped the bar before going over.
And Ogbonna's hesitancy in the 47th minute threw a cat among the pigeons.
On came Michail Antonio to make it two up top and slowly the momentum shifted as West Ham's threat increased. As soon as Petrovic erred, the writing was on the wall for the visitors.
Ghana winger Kudus will claim the headlines, but Ward-Prowse was the architect of the Hammers comeback. His two deadly, whipped corners quietly and efficiently taking him to five assists in just five games since joining the club from Southampton in the summer.
West Ham's success in Europe last season came with a perfect home record - seven wins out of seven.
It wasn't easy, but they've continued that form and will go to Freiburg for their second game on October 5 as Group A leaders, with the German side second after winning 3-2 at Olympiakos.