Alan Pardew feels the addition of Ben Thatcher can help give Charlton a 'harder edge' as they battle for Barclays Premiership survival.
The Addicks have completed a £500,000 swoop for the 31-year-old former Wales defender, while also offloading summer arrival Djimi Traore to Portsmouth - taking a loss of £1million in the process.
Pardew maintained he had to 'shake up' his back four, which has conceded 40 goals in the Premiership so far.
The Charlton manager feels the arrival of Thatcher - who served an eight-match ban earlier this season following his horror challenge on Portsmouth's Pedro Mendes - will do just that.
Pardew said: '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.
'I looked at Ben, saw he was available and that he would improve us.'
Thatcher himself is relishing a 'fresh start' at Charlton.
The defender said: 'I am looking forward to the challenge of helping to keep Charlton in the Premiership this season.
'It is a fresh start for me and I am looking forward to working with Alan Pardew, who I have always respected as a manager.
'We have got a massive game against Middlesbrough on Saturday and I hope that I can play my part and help the team to a big three points.'
Thatcher told the club's official website: 'I am confident that with the players that are already here, and hopefully a few more additions to the squad this month, Charlton will stay up this year.'
But the Charlton boss is troubled by the damning statistics of Charlton's season so far.
'We have conceded more goals than anybody else, and I feel we need a bit more dialogue in the back four,' he said.
'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 kickstart our season.'
Pardew has no qualms in throwing Thatcher straight into action against Middlesbrough on Saturday, and would not keep him away from any potential hot reception at Portsmouth next week.
'Ben is a committed player, and fans know he will put a tackle in fairly and play good football for Charlton,' said Pardew.
'I am going to handle him the same way I have done others who have come to me with similarly bad disciplinary records. I think Lee Bowyer has had one booking so far this season when I was at West Ham.'
'You just have to be very stern and strict about it and make sure there are guidelines to what they can and can not do.
'You can not ever stop a moment of madness, of course. Some players with the calmest of temperaments can do that, as (Zinedine) Zidane showed in the World Cup final.
'But on the whole, I think you can put things in place that can limit the damage in terms of suspensions and sendings-off.'
Souleymane Diawara could also follow Traore to the south coast as part of a swap deal for Andy O'Brien, although Pardew today stressed 'at the moment it is not going to happen.'
The Charlton boss insisted: 'I need to do everything I can to keep the club in the Premiership. Whatever that is, I will try to do it - regardless of what has been paid and reputations have been gained.
'It is all about the here and now, and we need to change it around to make sure we do.'
Pardew still hopes a deal can be finalised for unsettled Sevilla striker Kepa Blanco - and re-iterated his intention to retain the services of leading scorer Darren Bent.
The England striker is currently sidelined with a knee problem, and Pardew admits that made him briefly consider the option of cashing in on the £12million man to release an injection of funds.
But with Bent now well on the road back to fitness, the Charlton manager said: 'The decision about selling Darren has gone away, and he will stay here until the end of the year.
'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.'
Midfielder Andy Reid and defender Hermann Hreidarsson are set to return to the squad this weekend, but captain Luke Young (knee) still needs a couple of weeks.
Recent signing Zheng Zhi will also not yet feature, the China captain having only just arrived in England.
Pardew said: 'It is a huge adjustment for him to be in this country - let alone to the type of football that we play - but he has approached it with a smile on his face.'