While Arsene Wenger finds himself in a familiar situation, Pep Guardiola heads for uncharted territory. Should Chelsea win today, Arsenal will be nine points behind the Premier League leaders, Manchester City 10.
As perhaps the two purest footballing sides in the division clash, it is with a pragmatic requirement for points.
The Frenchman is in a defining week of difficult away games but the Catalan is unaccustomed to playing catch-up to such an extent. It is why this is a bigger game for Guardiola.
With Liverpool beckoning, a month that has already included defeats by Leicester and Chelsea has the potential to prove a hugely damaging December for City.
So this is a test of Guardiola's powers of recovery and strategic skills. He does not have the players to replicate the physical approach that worked well for Everton against Arsenal on Tuesday.
Combined number of clean sheets Manchester City (two) and Arsenal (none) have in their last seven games.
His own bold decision to deploy a 3-2-4-1 formation against Chelsea, which might have worked had City been better in either box, and Leicester, where it backfired dreadfully, left him looking naive.
City's capacity to be counter-attacked should suit an Arsenal side with the pace of Alexis Sanchez, Theo Walcott and Alex Oxlade-Chamberlain.
Their width means Guardiola has to start tomorrow's clash with a back four, as he did in Wednesday's win over Watford.
Whatever his choices, entertainment is promised. City have just three clean sheets in 16 league games and Arsenal none in seven, so goals seem guaranteed.
Both have been accused of being too open, but the Gunners can nevertheless prove role models to their hosts.
Francis Coquelin came of age as an Arsenal player when they won 2-0 at the Etihad in January last year, showing a team long deemed soft touches on the road have grown more savvy against City.
The Frenchman assumes a greater importance on a return, partly in tracking Kevin de Bruyne and David Silva and partly protecting a defence denied the injured Shkodran Mustafi. The German has never lost a game as an Arsenal player; three days after he was injured, they were beaten 2-1 by Everton.
It leaves Wenger looking to construct another nine-month unbeaten away run.
He has long argued that his side show character. They will require it again, along with concentration as England's most intricate and innovative teams in possession meet.
Arsenal include some Guardiola-style players, including Sanchez, whom he signed for Barcelona, and Hector Bellerin, a putative target for City, while Wenger signed Bacary Sagna and Gael Clichy and once expressed an interest in Raheem Sterling. They both prioritise pace, movement and attacking intent.
There is a commonality of ideas. While opposites collide in some games, here the likenesses are more pronounced. It renders it more interesting, but perhaps also more demoralising for the eventual loser if shortcomings are exposed by a similar side.
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