The Gunners found their season at the crossroads when they were two goals behind at half-time after Richard Dunne headed home Robbie Keane's cross from the left side of the area in the 32nd minute before Darren Bent forced a save from Lukasz Fabianski from an angle before slotting home the rebound from an even sharper slant.
It was definitely a game of two halves as Arsenal looked well under-par in defence and devoid of any attacking creativity in the first half but were able to completely turn their performance around in the second term.
Less than 10 minutes into the second lot of 45 minutes, Arsenal had drawn one goal back when Alex Song slipped in a through ball for Aaron Ramsey who took a touch and was then brought down in the area by Dunne. Robin van Persie stepped up to the spot and sent Shay Given the other way to make it 3-1.
Two minutes later and the Gunners were just a goal behind when Theo Walcott made a marauding run down the right to see his cut-back from the byline deflect off Alan Hutton, back onto his chest, and into the back of the net before van Persie again slotted home from the penalty spot after Bent had clumsily challenged Laurent Koscielny.
The second of the Dutchman's spot kicks put him equal with fellow countryman Dennis Bergkamp on 120 goals for the club and allowed them a path through to the next stage where they will meet the winner of the Sunderland v Middlesbrough replay at either the Stadium of Light or the Riverside Stadium on the weekend beginning February 17.
Emirates Stadium, London