The Gunners went into Monday night’s Premier League clash at St James’ Park knowing victory would leave them in pole position to claim a top-four place ahead of arch-rivals Tottenham when they entertain Everton on Sunday.
However, a 2-0 defeat on Tyneside means their fate is out of their own hands, with Spurs two points clear in fourth with a far superior goal difference and knowing a single point at Norwich is likely to be enough to see them home.
Arteta said: “We need to win and we need a defeat for them. We know in football, that’s always possible and if anything happens, you have to be there in order [to take advantage].
“Today, you have to put your head down, swallow all the poison that we all feel, hopefully, and tomorrow start again.”
Arsenal ran out knowing exactly what was at stake, but were never really able to compete with a Magpies side backed by a raucous crowd of 52,274 from the off.
Newcastle took a 55th-minute lead through Ben White’s own goal and then cemented victory when the once again hugely impressive Bruno Guimaraes extended their advantage with his fifth goal since his £35million January move from Lyon.
Arteta said: “Normally I sit here, I can defend what we have done. Today, it’s not easy. Newcastle were 100 times better than us in every department from the beginning to the end, and it’s very hard to accept it.
“But that’s the reality of what happened today on that pitch.”
Gunners midfielder Granit Xhaka’s assessment was even more damning.
He told Sky Sports: “We didn’t do what the game-plan was, not listening to the coach. We were doing our things and when you do your things, this is what happens.
“You don’t deserve to play Champions League, you don’t deserve to even play Europa League. It’s very hard to take and I don’t know why we don’t do what the coach is asking of us.
“We need people to have the balls to come here and play, because we know this is one of our most important games. But a performance like this is not acceptable and very sad. I feel very sorry for Arsenal supporters.”
Magpies boss Eddie Howe was understandably jubilant after a performance he rated as the best since his arrival at the club in November, when relegation was a very real possibility.
Asked if he could have envisaged the current situation – Newcastle head for Burnley on Sunday with a top-10 finish still a possibility – he said: “It probably could have gone better – of course it could have done in certain games and in certain moments.
“But when you look back as a whole, if you’d have said this would be the outcome and this is how you will achieve safety in the division, certainly in some phases of a season, I would have been surprised if you’d told me that would have happened.”
Geordie TV presenters Ant and Dec were among those who congratulated Howe and his players on the final whistle, much to the former Bournemouth manager’s delight.
He said: “They were so complimentary about the team and the work that we’ve done, so that was a really nice moment because it brings it home how much everyone cares about Newcastle and how much it’s the centre of their lives, so that meant a lot.”