Manager Manuel Pellegrini was keen on the Uruguayan as he sought for a quality finisher, but the South American wants to join Valencia instead.
£40 million-rated Zapata can offer West Ham exactly what they need, though, after scoring 26 goals in 42 games across all competitions for Atalanta last term during a loan spell.
At 28, the Colombia international is at the peak of his powers, and could guarantee the Hammers the goals they need to break into the top seven.
West Ham were once keen on Zapata earlier in his career, and could now finally secure his services this summer.
Having played for the likes of Napoli and Udinese, the former Estudiantes brings a lot of quality experience to the table.
At 6ft 2in, Zapata is as much as a physical presence upfront as the 6ft 4in Arnautovic, and he definitely can replace the Austrian goals and do more at the London Stadium.