Lee Clark hailed the loan system after Birmingham City opened up a four-point gap on the bottom three in the Sky Bet Championship.

A double from Manchester United's Federico Macheda gave Clark's team victory at Charlton.

Macheda grabbed a goal in each half, making it three goals in two games for City since signing on loan at the end of January.

Blues boss Clark explained: "I lost five players on loan on New Year's Day and had to rebuild the squad.

"It took a while and we lost three league games which knocked the stuffing out of us.

"Luckily I was able to recruit new players and they have done very well for us.

"We have got got a bit of a conveyor belt from Manchester United and we thank David Moyes for helping us.

"I only hope they don't do so well and they then go back early."

The defeat leaves Charlton without a win since Boxing Day and stuck in the bottom three, with manager Chris Powell concerned for his future.

He said: "I have not spoken to the owner about the future as yet. I will catch up with him after the weekend.

"We need results and we are not getting them I understand the need the to push away from the bottom.

"I would rather have more points than still be in the cup but we will be trying hard to get into last eight."

The Addicks handed home debuts to striker Reza Ghoochannejhad and winger Astrit Ajdarevic, while fellow new signing Yoran Thuram-Ulien started in goal.

All three players were signed from Standard Liege, another of the football clubs owned by Charlton's new owner, Belgian millionaire Roland Duchatelet.

Powell knows they have to fit in quickly, and said: "We had to involve them in everything we do.

"They have to get used to us and the way it is in the Championship if they want to add their qualities to the squad and get into the swing of things.

"It was a big moment for them playing here for the fist time."

City went ahead in the 22nd minute when Manchester City loanee Emyr Huws put in a free-kick from Birmingham's right wing and Macheda got enough of a head on it to claim his second goal in as many goals since signing on loan from Manchester United on deadline day.

Randolph also saved a spectacular scissors-kick effort from Ajdarevic, then pushed away a half-volley through a crowded box from Johnnie Jackson.

The City stopper, who has played every minute of the league season, was determined to keep his seventh clean sheet of the campaign and had to be sharp to push away a shot from Ghoochannejhad - which looped off a defender - and a long-range effort from Marvin Sordell.

Powell added: "We acquitted ourselves well with some good passages of play. We had good chances but their keeper did well.

"In the end it was not our day, we had opportunities to score. The chances were there but Birmingham scored at crucial times."

There was an inevitability about their winner 10 minutes from time when they caught Charlton on the break.

Free summer signing Tom Adeyemi made a breakaway dash from the halfway line before sliding the ball in for Macheda and he took a touch before beating Thuram-Ulien.

Clark was impressed with the second goal, adding: "Adeyemi is a powerful young man and developing all the time.

"I knew what he could do at Norwich and I totally believe in him.

"It was a great run and then he had the presence of mind to know where the pass had to go.

"Then Federico showed a touch of quality to finish."