Addicks manager Alan Curbishley made six changes in a bid to halt his side's poor recent form.
Myhre became the club's third Premiership keeper of the season and on-loan Uruguayan Gonzalo Sorondo came in at centre-back. Sorondo was partnered in central defence by Jonathan Fortune so Hermann Hreidarsson switched back to left-back.
There were also changes across midfield with Alexei Smertin and Jerome Thomas ruled out with a knee niggle and illness respectively. So Curbishley opted for a 4-4-2 system with Matt Holland and Bryan Hughes joining Murphy and Radostin Kishishev across the midfield. Up front Shaun Bartlett joined Darren Bent.
From the outset Charlton certainly showed much more spirit than of late, snapping at the heels of their capital rivals. However, they lacked any real quality to test Arsenal.
But having worked so hard in the opening juncture Arsenal had the opportunity after 22 minutes when they should have taken the lead. Reyes made good ground on the left and slipped the ball through for Ljungberg who broke clear through the middle as Murphy switched off but the Swede delayed his shot.
Myhre stood tall and did well to with his legs to deflect the ball away for a corner.
Charlton's chance came two minutes before the interval when Bartlett's precise pass sent Bent racing away on goal, but just as the striker was about to shoot Sol Campbell saved the day for the visitors with a superb last ditch retrieving tackle. Then moments before the break Murphy was carded for bringing down Hleb.
After Arsenal's goal, eventually converted by Reyes Charlton were forced back and, as the visitors took control of the game.
Charlton suffered a further blow when Sorondo hobbled off to be replaced by Jonathan Spector on 65 minutes. Then on 69 minutes Curbishley made his second change with Kevin Lisbie replacing Bartlett.
The home side’s uphill task became even harder for the hosts as they were reduced to ten men in the 72nd minute. Hreidarsson was fuming as he was adjudged to have fouled Gilberto - and Murphy gathered the loose ball before angrily bouncing in down in front of Referee Steve Bennett.
Unfortunately the official produced a second yellow card to send the midfielder packing for his overheated protest before Curbishley threw Darren Ambrose on for Kishishev, but his efforts to seek out an equaliser were in vain.