Albion striker Neal Maupay was at the heart of the action throughout.
The French striker lifted the ball over substitute Gunners goalkeeper Emiliano Martinez five minutes into added time to earn a much-needed 2-1 win for relegation-threatened Albion.
Martinez was only on the field because first-choice keeper Leno was stretchered off in the first half with a serious-looking knee problem following a nudge from Maupay.
Tempers ran high at full-time, with Arsenal midfielder Matteo Guendouzi appearing to put his hand around Maupay's throat - which could see Guendouzi face disciplinary action.
Alan Shearer, the BBC Pundit and all-time Premier League top goalscorer, had words of encouragement for Maupay. "It was just one of those challenges. It wasn’t malicious at all. He’s just sort of jumped into him and it was a freakish accident, unfortunately, and we hope the goalkeeper is okay."
His Match of the Day colleague Ian Wright added: "This is top quality play from him. And this is what he’s capable of doing. Knowing him, seeing him, watching him finish at Brentford, he’s very sharp in and around there.
"He was a nuisance all day, he’s got that about him, and he finished it very well.
"Him and Guendouzi had been having it all game and I think he was talking about Guendouzi at the end. He’s [Guendouzi] given him a bit there and he’ll probably get in trouble for that."
Karen Carney, the former England and Chelsea winger, was also impressed with Maupay. "What a goal. It started with a cheeky flick and it's a lovely finish. Maupay bends it round the keeper but what a team goal.
"There are no fans here but there was jubilation on the Brighton bench."
After the match Maupay expressed remorse for Leno's, although he was angered by the behaviour of unnamed members of the opposition.
"At half-time, I went to Arteta to apologise because I never meant to injure their keeper," Maupay said.
"I just jumped to get the ball maybe and I think he twisted his knee, I never meant to hurt him.
"I am really sorry. I apologise again and I wish him a speedy recovery.
"Arsenal players need to learn humility, maybe sometimes," added Maupay who also scored the winner for Brighton against Arsenal at the Emirates back in December.
"They have been talking a lot first half, second half when they were 1-0 up. They got what they deserved."
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