Michail Antonio and Declan Rice struck in each half to secure a 2-0 win for West Ham against Dinamo Zagreb in Thursday's Europa League opener.
Antonio opened the scoring as he capitalised on Kevin Theophile-Catherine's poor pass to finish into an empty net, before Rice doubled the lead five minutes after the break.
Luka Ivanusec almost beat Lukasz Fabianksi, who did not make a save all game, but that was Dinamo's only opportunity as West Ham secured their first win in European competition since 1999 to top Group H.
In contrast, Dinamo will be disappointed with their efforts at the Maksimir Stadium as their 13-match undefeated run in the group stage of the competition ended abruptly.
The visitors boasted almost 70 per cent possession inside the opening 15 minutes but, barring a barrage of corners, Aaron Cresswell's inaccurate long-range effort was their only half-chance.
However, Antonio made West Ham's dominance pay as he profited from Theophile-Catherine's concentration lapse to round Dominik Livakovic and score the Hammers' first goal in Europe since 1999.
Ryan Fredericks was then denied by the Dinamo goalkeeper's feet before Nikola Vlasic fired narrowly wide on the stroke of half-time.
Dinamo looked to respond immediately in the second half, with Bruno Petkovic blasting narrowly wide but it was Rice who added a second, driving forward before powering a left-footed strike through the legs of Livakovic.
Ivanusec tried to pull one back, dancing around Kurt Zouma prior to curling towards the bottom-right corner, only to see his effort trickle wide as Fabianski passed the hour-mark without making a save.
With David Moyes' men dominant, Pablo Fornals looked for a third with a low attempt but found Livakovic's hands as the visitors cruised to a memorable return to European football.
What does it mean? Moyes offers insight into rotation policy
While Antonio provides an exception due to his suspension, David Moyes named six players in his starting XI that lined up against Southampton in the Premier League, suggesting he intends to utilise his strongest side for the Europa League.
The decision was justified as the visitors dominated from start to finish with an authoritative performance in their first group stage appearance in European competition since 2006-07.
In contrast, Dinamo have now lost 12 of 18 fixtures against English opponents in European competition and with Genk defeating Rapid Vienna they will need to respond quickly in Group H.
Rice's goal made him the youngest Hammer (22 years, 245 days) since Frank Lampard (21y, 88d) in the 1999-00 campaign to score in a major European competition and that topped off a complete performance.
The midfielder completed 53 passes, misplacing just one, while finding a team-mate with every one of his 32 opposition-half passes as the hosts failed to deal with the England international.
Arijan Ademi failed to make an impact throughout in a performance that reflected Dinamo's timid showing.
Dinamo's captain touched the ball 40 times – the fewest of any outfield player to play the full game – and won just a third of his six duels as he struggled against Cresswell.
Key Opta Facts
- In their 20th game, West Ham are celebrating just their sixth win away from home in major European competition, one of which was the 1965 Cup Winners Cup final at Wembley (neutral venue). The Hammers managed their first goals (and victory) in a European encounter (excluding qualifiers) for the first time in five matches.
- Antonio is now the outright top goalscorer of all Premier League players in 2021-22, with his five efforts coming from only nine shots on target this season.
- Dinamo have now lost 11 of their last 13 matches against English sides in all competitions (W2), shipping 30 goals in the process.
- Antonio became West Ham's first goalscorer in major European competition (excluding qualifiers) since Marc-Vivien Foe against NK Osijek in September 1999.
West Ham host Manchester United in the Premier League on Sunday, while Dinamo face Orijent 1919 in the Croatian Cup in six days' time.