The 26-year-old spent six seasons with Standard prior to his move to Porto in 2011, and angered his old club's fans when he returned to join their fierce rivals Anderlecht at the start of this campaign.
Sunday saw him return to the Stade Maurice Dufrasne for the first time, and the home fans greeted him by unfurling a banner showing a figure holding a sword in one hand and Defour's severed head in the other, adorned with the words "Red or Dead".
The Belgium international was subject to taunts from the Standard fans throughout the Pro League clash, and with 55 minutes gone – and the score at 0-0 – he reacted.
Defour, who had already been booked, received a short pass in midfield before turning and deliberately firing the ball into a section of the home fans.
Referee Alexandre Boucaut swiftly issued him with a second yellow card.
His dismissal infuriated the travelling support and sections of the Anderlecht fans were shown on television throwing seats onto the pitch in anger.
A man down, Anderlecht could not keep Standard out as goals from Laurent Ciman and Igor de Camargo ensured a miserable afternoon for the visitors.
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