The Arsenal duo have kept 16 clean sheets in their last 27 games together
There are a few reasons why Arsenal's defence has tightened up recently.
The Gunners work harder to win the ball back while the signs of assistant manager Steve Bould's work on the training ground is beginning to bear visible fruit.
But it's no coincidence that since Per Mertesacker and Laurent Koscielny became the de-facto centre-half pairing at the club, Arsenal can barely do any wrong defensively.
As this Sky Sports graphic from last night shows, they are yet to taste defeat together as a pairing...
The duo complement each other's play with the slower Mertesacker hanging back to provide protection for the Frenchman who can engage the opposition forwards.