The Hammers go up against Arsene Wenger's side for the second time this month in the last eight of the competition, but will now be without his Argentinian dynamo after he was found retrospectively guilty of diving.
The Football Association have given him a two-game ban, after his theatrics won a penalty which was dispatched by captain Mark Noble. He is the second player to be banned after the full-time whistle for diving, following Oumar Niasse.
With Lanzini out and Edimilson Fernandes still struggling with an ankle injury, Moyes will be looking into the depths of his squad to find the kind of player capable of connecting the midfielder and strikeforce.
It should see his attention swing to 18-year-old summer signing Sead Hakšabanović, who has made just one appearance for West Ham's senior side so far following his move from Swedish outfit Halmstads BK.
Preferring an attacking midfield role, Hakšabanović is already a two-time Montenegro international and Moyes' faith should be placed in the youngster in what could be the break he needs to shine.
With Moyes likely to make changes anyway, Lanzini and Fernandes' absence should give Hakšabanović his proper senior chance against a side that are expected to surpass West Ham.
Lanzini has until 6pm on Tuesday night to detest the decision, but Moyes should hand his teenage prodigy a chance to dazzle London Stadium fans under the floodlights.
Have something to tell us about this article?