West Ham marked the official opening of their new home with a 3-2 defeat against Italian champions Juventus in front of a 53,966 crowd.
Paulo Dybala and Mario Mandzukic gave the visitors a commanding 2-0 lead at the former Olympic Stadium, now known as the London Stadium.
Andy Carroll pulled a goal back and then headed the equaliser before Simone Zaza hit the winner for Juventus.
West Ham left Upton Park – their home for the past 112 years – in the summer.
They overcame Slovenia’s NK Domzale 4-2 on aggregate in their first game at the London Stadium last Thursday to reach the Europa League play-off round.
West Ham’s first Premier League game at the venue, which hosted athletics at London 2012, is against Bournemouth on 21 August.