Johnnie Jackson netted the winner as Charlton Athletic picked up their second successive win and climbed out of the relegation zone courtesy of a 1-0 win over Birmingham City at St Andrews. 

Birmingham striker Clayton Donaldson was ruled out before the game with a groin injury and is expected to miss six weeks.

Birmingham, who won their last game 5-2 at Fulham, have now failed to win any of their last three home matches, whilst Charlton have back-to-back wins.

Jacques Maghoma had an early chance for Birmingham but his attempt was well saved by Stephen Henderson, before Charlton had a flurry of chances with Ademola Lookman going close on his debut, and Tareiq Holmes-Dennis forcing a good save from Thomas Kuszczak.

Charlton played a deep defensive line and this frustrated Birmingham, with Jon Toral and Demarai Gray both squandering chances.

The winner came when a cross from Holmes-Dennis was headed home by Jackson to give the visitors the lead. They almost doubled their advantage soon after when Ricardo Vaz Te was well denied by Kuszczak.

Ultimately, Birmingham were toothless in front of goal despite dominating long periods of the game.

FootballLeagueWorld writer Michael Hasan identifies three things that we learned from yesterday's encounter...

1) Lack of Birmingham squad depth

Birmingham found themselves in trouble as soon as Donaldson was ruled out through injury.

They simply don't have another striker in the squad good enough to take on Donaldson's responsibilities, and young Nicolai Brock-Madsen couldn't fill the void. The Blues were relying on the midfield popping up with goals.

This could become a serious problem for Birmingham as he is out for six weeks so an emergency loan may be in order.

If manager Gary Rowett wants to get into the play-offs with Birmingham, then they need to get back-up for Donaldson.

2) Karel Fraeye is surely up for the permanent role

A lot of names have been thrown in the hat for the Charlton job, but consecutive wins for Fraeye must make him a lead candidate.

He is the interim boss currently, but back-to-back victories over play-off chasing sides in Sheffield Wednesday and Birmingham helps him push forward a case for the permanent role.

He has them playing with a very deep defensive line, which is frustrating attacking lines but proving effective as they turn around their fortunes.

3) Cracks slowly forming in the Birmingham defence

When Rowett took over from Lee Clark last season, the biggest task he had was fixing their leaky defence, and their remarkable recovery he led was chiefly down to him sorting out the back four.

A key component of this defence was Michael Morrison, who has been immense for them since he joined from Charlton.

They started well this season, but in recent weeks the odd crack is showing and mistakes against Wolverhampton Wanderers and a sloppy goal to give away yesterday means Rowett may need to take another look at the back as shades of the old Birmingham are starting to show.

Birmingham and Charlton fans... what did you think of the game? Did Charlton deserve the win? Should Fraeye be given the job permanently? How much did Birmingham miss Donaldson? Let us know your thoughts and opinions in the comments below!