Charlton are in serious danger of dropping out of the top six after losing 3-1 to Southend on Boxing Day.

A Simon Cox brace and Michael Turner goal condemned the Addicks to a fourth defeat in six league games.

It means Charlton will lose their play-off spot if Peterborough, Rotherham or Portsmouth win later today.

Karl Robinson could only name six substitutes on the bench due to the Addicks’ depleted squad. Leon Best and Mark Marshall were the latest players to join the treatment room after suffering hamstring injuries against Blackpool.

However, Ricky Holmes and Ahmed Kashi returned to the starting line-up.

Charlton got off to the worst possible start when they conceded after just two minutes. Jason Demetriou’s deflected shot was headed on by Nile Ranger and slammed home by Cox. The Addicks’ defending was shambolic.

And before the visitors let in a second, they were lucky not to give away a penalty as Cox appeared to be tripped by Holmes.

Charlton’s vulnerability defending set-pieces was exposed again when they conceded from a dead-ball situation for the fourth successive game. Anthony Wordsworth’s delivery found Turner, who headed past Ben Amos on 11 minutes.

The Addicks, who didn't touch the ball in Southend’s box until the 16th minute, responded through Holmes’ effort which stung Mark Oxley’s palms.

And they should've pulled a goal back when Ben Reeves played in Karlan Ahearne-Grant, however, the youngster hit the side netting.

At the other end, Ranger spurned two chances to end the contest before the break. The former Newcastle striker dispossessed Kashi and had two Southend players to his left, but his pass was overhit. He then failed to keep his header down from close-range after connecting with Ben Coker’s cross.

Referee Darren Drysdale blew his whistle for half-time and Charlton players were booed off by the 1,000-plus travelling fans.

Amos pulled off a good save to stop Southend from adding a third just two minutes into the second-half when he denied Conor McLaughlin.

Ahearne-Grant and Joe Aribo threatened with efforts of their own as Charlton improved.

Reeves gave Charlton a lifeline in the 66th minute after scoring his first league goal for the club. Josh Magennis teed up the playmaker, who finished well.

Robinson’s men dominated possession but failed to create any meaningful openings.

And Cox volleyed in his second goal of the game on 79 minutes to compound Charlton’s misery.

Charlton XI: Amos, Dijksteel, Konsa, Sarr, Dasilva, Kashi (Lennon, 45), Aribo, Ahearne-Grant (Hackett-Fairchild, 87), Reeves, Holmes, Magennis.

Subs not used: Phillips, Dodoo, Jackson, Lapslie.