After Rhian Brewster was sent off for Sheffield United, West Ham had the easy task seeing out their 2-1 win at Brammall Lane.
But two quick yellow cards for Vladimir Coufal saw the right-back sent off in the 97th minute.
The free-kick found its way to James McAtee, who crossed into the box.
In a moment of madness, Alphonse Areola took out Oli McBurnie as he tried to punch the ball away and completely missed, wiping out the Scotland international.
Referee Michael Salisbury had no hesitation pointing to the spot to send the home crowd into a frenzy.
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The incident saw Areola injured and forced off as Lukasz Fabianski came in, immediately tasked with stopping the Blades from grabbing a last-gasp equaliser.
But McBurnie made no mistake from the spot to give Chris Wilder a crucial point in the relegation battle while David Moyes was left scratching his head.
More to follow