Brighton scored two goals from two shots on target to maintain their unbeaten start to the season with victory at West Ham, who remain without a league goal or a point.
The Hammers started the second half brightly but were undone when Leandro Trossard latched on to Pascal Gross's flick to inflict a third straight league defeat on the hosts.
Aaron Cresswell had a fierce effort well blocked by Joel Veltman, before Robert Sanchez produced two acrobatic saves late on to keep out two Tomas Soucek headers.
West Ham have now had 38 shots in their opening three league games without scoring a goal, while Brighton have equalled their longest unbeaten run in the top flight at eight games, stretching back to the end of last season.