Javier Hernandez was on target for West Ham, but it was a miserable end to a turbulent few days for the east London club, who had to sack their head of recruitment Tony Henry after claims he told agents they did not want to sign any more African players.
Anger and frustration towards the West Ham board from supporters is at an all-time high following the scandal, as well as an underwhelming transfer window which saw a club linked with Olivier Giroud, Michy Batshuayi and Daniel Sturridge end up with Jordan Hugill from Preston.
Indeed, the first chants of 'sack the board' were belted out from the away end even before Murray put Brighton ahead in only the eighth minute.
The goal came after referee Roger East allowed play to continue despite Aaron Cresswell's foul on Anthony Knockaert, and Gross immediately pinged the loose ball to Murray.
Amid the off-field controversy West Ham boss David Moyes is also dealing with a spate of injuries and indiscipline - Arthur Masuaku is still serving a lengthy ban for spitting and Michail Antonio was dropped in midweek for being late to a meeting.
So it is to the Scot's tremendous credit that he has, until now at least, been ekeing out the points which have been keeping West Ham at arm's length from the relegation battle.
Moyes is also starting to get a tune out of Hernandez, and it was the Mexican who started and finished the move for West Ham's equaliser, first laying the ball off to Mark Noble who in turn prodded it forward to Joao Mario just inside the area.
The Inter Milan loanee flicked the ball back to Hernandez, who brought it on to his right foot before sidestepping both Lewis Dunk and Gaeten Bong and burying a fierce drive into the top corner.
However, midway through the second half Brighton retook the lead with a bolt out of the blue from Izquierdo.
The Colombian winger collected the ball on the corner of the penalty area and, with everyone in the ground anticipating a cross, curled a stunning effort over the despairing dive of Adrian and into the top corner.
This time Moyes and West Ham had no answer and with 15 minutes left their misery was complete when Gross collected Davy Propper's pass on the edge of the box and rifled a low shot across Adrian and into the far corner.
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