Gianluca Scamacca scored his first West Ham goal as the Hammers won the first leg of their Europa Conference League play-off 3-1 against Viborg.
Italy striker Scamacca, David Moyes' marquee summer signing from Sassuolo, netted a first-half header on his full debut.
Jarrod Bowen added a second after the break and although Viborg pulled one back, Michail Antonio rounded things off with the third.
West Ham were without Declan Rice and Aaron Cresswell, as well as Moyes, with all banned for various indiscretions in the agonising Europa League semi-final defeat to Eintracht Frankfurt in May.
Republic of Ireland U21 midfielder Conor Coventry played 84 minutes against the Danish visitors.
Moyes watched on from the stands as almost £50m worth of his summer acquisitions combined to give West Ham a 24th-minute lead.
Former Burnley winger Max Cornet worked his way to the byline, cut back inside and lifted over a cross for Scamacca to head home at the far post.
Viborg were providing a sporadic threat and when Cornet gave the ball away striker Jay-Roy Grot was sent through on goal, with Alphonse Areola racing out to save with his legs.
The second goal arrived in the 64th minute when Bowen picked the ball up 30 yards out, surged forward and pinged a low drive into the corner.
But four minutes later Viborg halved the lead through a far-post header from Jakob Bonde.
Areola was forced into a flying save from Nils Mortimer to prevent the Danes from drawing level before Antonio scored the third with tap-in from fellow sub Said Benrahma’s pull-back.
Northern Ireland champions Linfield were on course for a superb result as they went 2-0 up away to RFS in Riga but the Latvian side scored in the 89th minute and injury time to leave things finely poised.
The Irish Premiership side had looked set to be taking a decent lead back to Belfast after Stephen Fallon and Joel Cooper scored in each half, with Petr Mares having missed an early penalty for the hosts.
But a header from substitute Kevin Friesenbichler reduced the deficit with two minutes left and Ziga Lipuscek then completed the comeback when he equalised in the sixth minute of added time.
Hearts lost two soft goals in two minutes after taking the lead in Switzerland as they fell to a 2-1 defeat by Zurich.
Lawrence Shankland gave Hearts the lead from the spot midway through the first half of the Europa League play-off first leg but the visitors were behind inside 12 minutes.
Adrian Guerrero equalised after Hearts failed to deal with a simple long ball, and then Blerim Dzemaili capitalised from some more poor defending.
There were further scares but Hearts emerged from their first European game in six years with a real chance of progressing at Tynecastle next week. The losers are guaranteed Europa Conference League group action.
In the same competition, Shamrock Rovers were beaten 4-0 by Ferencvaros in Hungary.