Arsenal manager Arsene Wenger has warned it could take West Ham at least two years for them to settle into their new surroundings at London Stadium.
After 112 years at Upton Park, West Ham moved to the bigger-capacity stadium in London ahead of the 2016-17 season, but it has coincided with the club struggling for form in the Premier League.
West Ham suffered a humiliating 5-1 loss to Arsenal on Saturday as they dropped to 17th in the table, only a point above the relegation zone.
Wenger, who oversaw Arsenal's relocation to the Emirates Stadium from Highbury in 2006, said West Ham need time to get used to London Stadium.
"It takes you over a year," Wenger said. "Two years, I think, to really feel [comfortable]. Because you have to create a history.
"At Upton Park, fans sit next to each other. You remember that five years ago, we beat Man City here, or Arsenal. And now, there is no history.
"So they have to recreate something where people share the experiences, and the players feel completely the confidence that they are playing at home and not on a neutral ground. It takes two years."