Centre-back: Laurent Koscielny
Thirty-three and still going strong, the French defender is having another memorable season with the Gunners.
He too had a difficult start to the season like Kolasinac when he missed the first 16 games due to Achilles tendon rupture. But he has successfully recovered from the tribulation and found his feet again.
The Arsenal skipper has beefed up the defence: without him in the starting line-up, the Gunners concede 1.44 goals a game, while the figures drop down to 1.0 with him.
Koscielny has also made 47 clearances and 20 interceptions but has demonstrated his offensive instincts with three goals too.
His talismanship would be vital if Gunners are complete a league double over their crosstown rivals.
Centre-back: Shkodran Mustafi
Barring the disaster against Liverpool in December, Mustafi has otherwise been going great guns at the heart of Arsenal's backline.
The German centre-back has thrown his weight around the defense with crucial blocks, tackles and clearances (a staggering 123!) though his passing range is his best asset.
Having completed 1,289 passes, Mustafi boasts an 85% pass success rate and helps build from the back as well as avert any danger.
He also has two goals to his name, both of which have been crucial - he scored the opener against Cardiff to set Arsenal on their way to a nervy 3-2 win, before repeating the feat at Old Trafford to help gain a valuable point against Manchester United.
Mustafi has a good track record against the Lillywhites, even scoring one last season. And on this evidence, may fancy his chance again tomorrow.