Mikel Arteta declared it a "new league" after Arsenal's defeat by Manchester City on Sunday — and it has since become exactly that. City's 1-0 victory over Burnley on Wednesday moved Guardiola's side above Arsenal on goals scored, with both clubs locked on 70 points and a +37 goal difference with five games remaining.

Having spent 209 days at the summit of the Premier League, Arsenal have now slipped to second place for the first time since August. The question gripping English football is whether the Gunners can — and must — change their approach in the run-in.

One-goal wins and a history lesson

Arsenal have won 10 of their 21 Premier League victories this season by a single goal — 48 percent of their wins. That is the highest proportion recorded by a potential champion since Leicester City lifted the title in 2016, when 61 percent of their wins were by the narrowest margin.

Wayne Rooney, who knows the pain of a title decided on goal difference better than most, believes the Gunners must shift their thinking. The former striker was part of the Manchester United squad that finished second behind City in the 2011-12 season — the campaign decided by Sergio Aguero's famous stoppage-time goal against Queens Park Rangers on the final day.

"Arsenal have been trying to nick 1-0 wins but they need to change that mindset and go at teams and win by three or four goals," Rooney said on the BBC's Wayne Rooney podcast.

Rooney added that, despite the momentum swinging toward City, he would "still have Arsenal as slight favourites." He recalled his former manager Sir Alex Ferguson's insistence that the team keep pressing for goals, warning that a title could — and did — come down to goal difference.

The irony is that Rooney himself benefitted from narrow victories in title-winning seasons. The 2008-09 and 2012-13 United sides both recorded 16 one-goal wins — 57 percent of their victories — and still claimed the trophy.

What the statistics reveal

Arsenal's attacking output this season paints a concerning picture. The Gunners are averaging 1.91 goals per game — 63 in 33 matches — putting them on course to become the first Premier League champions to average fewer than two goals per game since Leicester, who averaged 1.79 in 2015-16.

Only 60 percent of Arsenal's goals have come from open play, which would be a historic low for a title-winning side. They currently average 1.15 open play goals per game, and need nine more from their remaining five fixtures simply to match Leicester's record-low tally of 46 from that 2015-16 season.

Arsenal's projected goal difference of +43 — based on their current rate — would be the lowest since Leicester won the league with +32. Last season Liverpool lifted the title with +45, while the Premier League average for a champion stands at +50.

The psychology of the run-in

Phil Johnson, a chartered member of the British Psychological Society's Division of Sport and Exercise, told BBC Sport that Arsenal's dip in form as their lead grew was a familiar psychological pattern.

"They're so close to the finish line that for a moment they imagine that they've already won — their bodies and their brains just kind of relax that little bit more and they get pipped to the post," Johnson said.

Johnson, who has worked with clubs including Liverpool, Everton, and Monaco, noted that when Arsenal were nine points clear, the team's energy visibly dropped. "They weren't offensive in terms of tackling and regaining possession, except when they were pushed hard," he added.

He believes Arsenal retain the quality to respond. "When Arsenal wake up, they can be absolutely phenomenal and they're also very creative. If they get this right then they can stay where they are."

Arsenal travel to face Newcastle on Saturday carrying that renewed pressure — and the knowledge that three more goals, or a single slip by City, could swing the title back in their favour.