Arsenal's memorable 3-2 home win over Liverpool on Sunday afternoon was somewhat marred by an on-pitch bust-up between Gunners defender Gabriel Magalhaes and Reds skipper Jordan Henderson.
The pair were embroiled in a heated exchange of words and squared up to each other in the aftermath of Michael Oliver's decision to give Arsenal a penalty late in the second-half. A seething Gabriel looked incensed during a coming together with Henderson, in which words were exchanged.
Young Arsenal star Bukayo Saka took himself away from the melee before stepping up to convert his spot-kick and win the game for the hosts. But there is no shortage of fallout from the fixture, with the FA now involved and investigating the incident. Mirror Football looks at what we know and what will happen next.
What happened
Following Thiago's clumsy attempted clearance that caught Gabriel Jesus, Oliver pointed to the penalty spot sparking a furious reaction from the Liverpool players.
Footage shows that things boiled over when Henderson appeared to say something, which Gabriel took exception to. At that moment, the pair were slightly separate from the huddle of players stood inside the penalty area.
The Brazilian international, clearly unhappy and gesticulating with his hands, angrily confronted the Reds captain who stood still and argued back. Before things could escalate further between the two of them, Kostas Tsimikas pushes between the two.
Gabriel shares an exchange with international teammate Roberto Firmino, before marching once more over to Henderson, still appearing to be furious. Granit Xhaka steps in too, before Gabriel turns to talk to referee Oliver.
Liverpool midfielder Thiago attempts to calm him down before Oliver calls over Gabriel to talk to him. The Arsenal defender, still unhappy, can be seen pointing in Henderson's direction. While this is going on, the Liverpool captain is in discussions with Xhaka.
Oliver eventually calls over both Gabriel and Henderson for a talk, doing his best to intervene and calm things before heading over to the dugout to discuss what had happened with both bosses.
What did Michael Oliver do
As tempers on the field started to fizzle out, Oliver sprinted over to the touchline to inform Mikel Arteta and Jurgen Klopp what had allegedly been said.
It prompted a brief delay to proceedings, as he explained the situation to both, as well as the fourth official.
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What happened after the game
Both managers held discussions with Oliver after the full-time whistle. Witnesses told Mirror Football that the situation had calmed down in the tunnel area post-match.
Oliver also asked for an assessment of what happened from both players involved, getting both Henderson and Gabriel's version of events before they both left the Emirates, to include in his official report to the FA. Liverpool captain Henderson was due to do post-match interviews after the game but was taken off his duties.
Klopp and Arteta were both pressed for comment on the situation during their post-match media pressers, but both insisted that they could not divulge any information while the incident was being looked into by the FA.
Arsenal boss Arteta did say however: "It was an incident that happened. Whatever happens on that pitch, stays on that pitch."
The game was televised on Sky Sports and presenter Dave Jones tried to add some clarity for those watching at home by breaking the incident down.
"What we understand has happened is something has been said on the field," he added. "The referee, Michael Oliver, has come over to speak to the managers and what we're being told now is that that matter has been referred to the Football Association. And any further comments on it will come from them."
What have the FA said
A spokesperson for the FA explained: "We are aware of an incident that took place during the match between Arsenal and Liverpool. We are in dialogue with the match officials and will review the details of the incident."
While the FA have issued an update, there has been no comment from any representative from either player or club.
Arsenal and Liverpool have handed over video evidence and it is likely that players who were nearby will also be spoken to for their version of events.
What happens next
The FA have transcripts of both players involved giving their account and will use them before making any kind of decision.
At this stage it is unclear what course of action the governing body will choose to take beyond their initial probe.
It remains to be seen whether Gabriel's discussion with Henderson after the full-time whistle did anything to ease the situation and also what exactly Oliver put in his post-match report.