Lanzini ruptured his cruciate knee ligament and is expected to be out for at least six months.
Argentina have a wealth of attacking options to choose from, with names such as Sergio Aguero, Gonzalo Higuain, Paulo Dybala, and, of course, Lionel Messi making other national teams a different shade of scarlet with envy.
Jorge Sampaoli chose to pick Lanzini ahead of Inter Milan forward Mauro Icardi, who scored 29 goals in Serie A last season.
Sampaoli originally named a 35-man provisional squad for Russian Federation and will likely select a replacement from the 12 players he dropped for his final group. Argentina have been drawn in Group D alongside Iceland, Croatia and Nigeria.
The seriousness of the injury also means Lanzini is likely to miss the opening games of the 2018-19 Premier League season. The thrilling playmaker is a fan favourite amongst Hammers supporters, and this most recent season has completed 27 appearances with a return of five goals and seven assists. He could move Mark Arnautovic to that spot to start the season if West Ham is able to keep him.