Arsenal kept the heat on Chelsea at the top of the Premiership table with a hard-earned victory over Birmingham.
Robert Pires' strike from the edge of the area put Arsenal in control after an error-strewn opening half-hour.
Thierry Henry burst through on 80 minutes to double their lead and his simple header soon after wrapped things up for the defending champions.
Birmingham offered little going forward and seldom troubled Manuel Almunia, in for the dropped Jens Lehmann.
Arsenal dominated possession early on, but looked nervous as misplaced passes and poor first touches prevented them establishing any rhythm.
Birmingham suffered a similar lack of composure, with long balls to Emile Heskey the limit of their initial attacking threat.
As both sides struggled to string passes together there was some light relief for the crowd when Robbie Savage was laid out after Pires' cross caught him full in the face.
But with so much of the ball the Gunners did work some openings, despite the energetic defensive efforts of Birmingham's five-man midfield.
Pires fired high on 10 minutes and soon after Jose Antonio Reyes' intelligent header put Henry in space on the right, only for the Frenchman's cross to drift harmlessly out of play.
Almunia, who had barely touched the ball as Birmingham continued to toil, had to be sharp on 30 minutes as a misjudged Cesc Fabregas backpass forced him to boot the ball out.
And two minutes later, Pires settled Arsenal's nerves with the opener.
Pires played the ball in from the left of the area to Ljungberg, took a stabbed return and delivered a superbly-struck low shot that just eluded Maik Taylor's reach.
Birmingham began to press forward after the interval, but their ambition simply provided the space for Arsenal that had proved so elusive in the first half.
It was almost an hour before Birmingham had their first shot on goal and it was a tame - and wide - effort from Heskey.
Birmingham brought on striker Clinton Morrison to partner Heskey in attack, and the Republic of Ireland international almost embarrassed Almunia with his first touch.
Birmingham's five-man midfield made life difficult for Arsenal
A long ball from Savage found Morrison in space and his first-time shot on the turn crept through Almunia's grasp and towards the goal-line but the keeper recovered just in time.
Birmingham continued to probe for an equaliser but never got close to seriously testing Almunia again.
And it was Arsenal who scored next as a trademark Henry goal made the three points safe on 80 minutes.
Taking a pass from substitute Gael Clichy, Henry turned Kenny Cunningham before outpacing Mario Melchiot in the box and coolly sidefooting past Taylor.
Six minutes later, Ljungberg's surging run down the right was followed by a perfect cross that allowed Henry to nod in from almost under the crossbar as Arsenal powered to their deserved victory.
Arsenal: Almunia, Lauren, Toure, Campbell, Cole, Ljungberg,
Vieira, Fabregas (Flamini 72), Pires, Reyes (Clichy 67), Henry.
Subs not used: Lehmann, Senderos, Owusu-Abeyie.
Goals: Pires 33, Henry 80, 86.
Birmingham: Maik Taylor, Melchiot (Martin Taylor 81),
Cunningham, Upson, Clapham, Johnson, Savage,
Anderton (Gronkjaer 57), Gray, Dunn (Morrison 67), Heskey.
Subs not used: Bennett, Yorke.
Ref: D Gallagher (Oxfordshire).