David Moyes was pessimistic that West Ham have the depth to compete on every front but their FA Cup journey will continue thanks to Manuel Lanzini and Jarrod Bowen.
In the first of two straight meetings with Leeds, first in the cup and then in the league, West Ham looked to punish a striker crisis for the visitors.
They went ahead in controversial circumstances when Lanzini scored and a review by the VAR found Bowen was not interfering with play despite being in an offside position.
It would be Bowen who would have the final say as with Leeds pushing desperately for an equaliser they were caught high and a long ball over the top sent Michail Antonio clear.