'Ruthless' Arsenal back in Premier League title race, says Arteta
Arteta's second-placed side moved within two points of Liverpool thanks to a dynamic display at the Emirates Stadium and a helping hand from a mix-up between Liverpool goalkeeper Alisson Becker and defender Virgil van Dijk.
After taking an early lead through Bukayo Saka, Arsenal were pegged back late in the first half by Gabriel Magalhaes's own goal.
But Liverpool gift-wrapped Arsenal's victory after the break when Alisson raced off his line to deal with a long ball and completely missed his clearance, with Van Dijk also failing to react in time as Gabriel Martinelli slotted into the empty net.
Liverpool had Ibrahima Konate sent off in the closing stages before Leandro Trossard's stoppage-time strike, which went through Alisson's legs after deflecting off Van Dijk, sparked a wild celebration from Arteta.
Defeats against West Ham and Fulham in the league over Christmas, coupled with an FA Cup third-round loss to Liverpool, had raised the prospect of Arsenal falling apart.
But Arteta knows they have blown the title race wide open with their priceless three points.
"We were ruthless when we had a chance and it feels like a big win," he said.
"At the moment Liverpool are probably the best team in Europe and the levels they have, they are an incredible team.
"We have come so far and now it is about doing it consistently. Liverpool have done it for six to seven years.
"It gives us momentum and the way we have done it we are back on it. I'm really excited."
Arteta admitted he knew how significant it was to beat Liverpool, who would have gone eight points clear of the Gunners with a victory.
'Could not feel sorry for ourselves'
"It was a huge game that was going to dictate where we are and where we're going to be," he said.
"What the players produced was phenomenal. Especially with the performance we had in the first half and the chances we created, the way we conceded was painful.
"We could not feel sorry for ourselves, we needed to react and there was a lot to play for. We went out and suffered a bit.
"Basically the message was there are going to be difficult moments and we had to navigate through them. Tonight we will enjoy it because we worked so hard to win it."
Liverpool boss Jurgen Klopp refused to condemn Alisson for his part in the disastrous defeat.
"It just shows the boys are human beings. Today we were really human. We gave them all the momentum," he said.
Van Dijk defended Alisson, saying: "I take full responsibility for that. That is a big moment in the game.
"I should have made a better decision. Alisson touched me a little bit and he couldn't clear it. I should have tried to clear it."
As he digested Liverpool's first domestic defeat in all competitions since losing at Tottenham in the Premier League in September, Klopp admitted he had no complaints about the result.
"Congratulations to Arsenal. We were not good enough today. We can say they deserved the points," he said.
"We found a way into the game. No shots on target but we scored a goal. Second half, we had our moments and then we concede that goal. That doesn't help.
"They scored goals and were many parts better than us. We have to play better football, that's clear. We were not involved in the game enough."