Charlton have completed the signing of Ben Thatcher from Manchester City.
Thatcher will help fill the void left by Djimi Traore's departure to Portsmouth.
City boss Stuart Pearce was willing to let Thatcher leave as he looks to raise funds for his own transfer plans.
Charlton chief Alan Pardew believes Thatcher will bring a competitive edge to his squad as they look to climb out of trouble at the wrong end of the table.
"I feel we are going to need a tougher, harder edge if we are going to get out of this - and I do not mean that in an undisciplined way," said Pardew.
"I looked at Ben, saw he was available and that he would improve us.
"We have conceded more goals than anybody else, and I feel we need a bit more dialogue in the back four.
"Ben Thatcher brings great experience and spirit to the team, and strength. He is going to be the sort of character we are going to need.
"I just feel we need to strengthen up a bit and need a bit more experience of what the Premiership is about.
"We do not need wholesale changes, just a few players to freshen things up and kick-start our season."
Pardew also reiterated his desire to keep Darren Bent at the club.
Bent, who is currently recovering from injury, has been strongly linked with a move away from Charlton during this month's transfer window.
However, Pardew insists the England international will remain at The Valley.
"The decision about selling Darren has gone away, and he will stay here until the end of the year," insisted Pardew.
"We think there is an outside chance that he could be ready for Manchester United, or West Ham the following week.
"It has been hard for him with all the speculation, and I opened the door to that - but I have said to him I have now closed that door firmly, so that he can focus on the rest of the season.
"Darren is a big player for this club - perhaps our biggest player.
"We will get him back as quickly as we can and then we will have a better chance to stay in the Premiership."