The talented youngster could be out for five weeks.
The 23-year old suffered a knee injury while preparing to represent Argentina at the Rio Olympics and he will now miss the start of the Hammers’ league campaign.
West Ham manager Slaven Bilic
"Unfortunately for us, Manuel Lanzini's injury is a blow. It's not a big injury but he can't play for the next four or five weeks," said Bilic.
The skillful attacker was a revelation last season - following his move from Al Jazira - scoring seven goals and creating a further two in 30 appearances.
West Ham's Manuel Lanzini celebrates scoring with Dimitri Payet
Bilic’s men face Slovenian minnows NK Domzale tomorrow in what will be their first competitive game at their new stadium.
West Ham's co owner David Gold poses outside the construction of the Olympic Stadium
They will need to overturn a 2-1 deficit if they are to progress to the next stages of Europa League qualification and keep alive their hopes of hosting European nights at the Olympic Stadium.
Mark Noble’s penalty has given Bilic’s men a vital away goal last week and with a packed home crowd roaring them on, the Hammers will be confident of getting the job done.