In a huge contest at Upton Park between West Ham United and Arsenal, the game has already been embroiled in controversy.
Indeed, Hammers ace Manuel Lanzini thought he had given his side the lead, but the strike was wrongly ruled out for offside.
West Ham, of course, have been on the wrong end of a number of high-profile decisions recently, so this latest mistake has, unsurprisingly, riled the club's faithful, who have taken to Twitter to express their anger.
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And, unfortunately for Slaven Bilic's side, things got even worse for the club moments later, as technically gifted German star Mesut Ozil handed Arsenal the lead.
The former Real Madrid star notched his sixth league goal of the campaign after accurately slotting the ball past West Ham shot-stopper Adrian. Incredibly, though, it's debatable whether Ozil's goal should have counted as he appeared to be in an offside position.
Here's the goal that was wrongly ruled out for offside:
Here's Mesut Ozil's opener for Arsenal:
Social media reaction
Here are the best tweets following the shocking decision:
The Gunners, who are still hoping to secure the Premier League title this term, can't afford to drop points this afternoon and it's crucial that they maintain their lead.
West Ham, on the other hand, still hold a chance of securing a place in the Champions League, but must find a way of securing a result against their London rivals.
Alexis Sanchez has since handed Arsenal a 2-0 lead; you can see the goal here:
What do you make of the decision to rule out Lanzini's goal? Have your say below!