Gianluca Scamacca scored his first West Ham goal on Thursday to help secure a 3-1 win over Danish minnows Viborg in the Europa Conference League play-offs.
West Ham, who made the Europa League semi-finals last season, went into the game after back-to-back losses in the Premier League to Manchester City and Nottingham Forest.
But Italian international Scamacca, signed for £30 million from Sassuolo, eased the nerves by finding the target in the 23rd minute after being teed up by another new signing, Maxwel Cornet.
Jarrod Bowen added a second in the 64th minute before Viborg pulled one back through Jakob Bonde five minutes later.
Twelve minutes from time, substitute Michail Antonio scored a third for West Ham to put the Londoners on course for a place in the group stage.
Villarreal, who were Europa League champions in 2021, overcame an early shock to defeat Hajduk Split 4-2.
Former Arsenal star Mesut Ozil was left on the bench as his Turkish side Basaksehir were held 1-1 by Antwerp in Istanbul.
Cologne, third in the Bundesliga after two games, lost 2-1 at home to Fehervar of Hungary.
In the Europa League, Hearts gave up a 1-0 lead to lose 2-1 at Zurich but will start the second leg as favourites next week in their first European tie in six years.