English Premiership: Sol Campbell, Portsmouth's centre-half, returns to his old club Arsenal today renewed after his messy exit and with his form and smile back, writes Jon Brodkin

Sol Campbell is larking about in goal after training at Portsmouth. Several team-mates have trotted off but the centre-back is not ready to head home yet. He is fielding shots, diving to push some away while others fly past. All the while he sports a large grin.

"Look at him messing around," says his manager, Harry Redknapp. "He's like a little kid. He's enjoying his football. He enjoys coming into work."

Not everyone imagined Campbell would cut such a figure again. A traumatic last season at Arsenal saw him hampered by injury and personal problems and he briefly disappeared to Brussels after deciding halfway through a defeat by West Ham he could not go on.

Campbell seemed spent and the enjoyment to have been sucked from his professional life. When he returns to Arsenal today, it is with his form and smile back.

The 32-year-old is a key reason why Portsmouth arrive at the Emirates Stadium in fourth place, one behind their hosts. Whereas Campbell played only 20 Premiership games for Arsenal last season, he has already appeared in 16 this term, missing one because of a stomach bug. Body and mind look strong again and have needed to be because, as Campbell knew, people doubted him.

"In life, once you go above the parapet people want to see what's happening or doubt you," he says.

"That's in any industry. The main thing is to believe in yourself, and I've always wanted to play football. I was ready to play and I'm happy playing and that's what it's all about. I've got the drive."

That is an element many imagined had gone.

"No," Campbell says. "I think sometimes you just need a new challenge in life."

As the defender glances around Portsmouth's spartan training ground and jokes that "it's definitely a challenge down here", he seems more at ease and less intense than amid the glare of being an Arsenal and England player. The conditions are hardly what he was used to but perhaps that even appealed given how he viewed his task when he moved on.

"You've got to start all over again and work your way up, and I don't mind doing that," he says. "It's a challenge in itself."

That seems a neat fit, with club and player seeking regeneration. Campbell was aware Redknapp would make several keynote signings - David James, Nwankwo Kanu and Glen Johnson - and has witnessed progress off the pitch, too. Rumour has it the showers were broken when he signed.

"I haven't got a clue but it was cold in there," he says.

"We've got a new facility and the guys at the top have paid to get that up and running. At least there are hot showers, and nice facilities for the physios to come in and do their stuff. Everyone can feel the club is going in the right direction."

The indications when Arsenal released Campbell last summer were that he would move abroad but nothing suitable emerged. Fenerbahce were among the interested parties.

"They were there floating about but things weren't really concrete," Campbell says.

"I talked to a few clubs, here and abroad, half and half."

Domestic suitors included Newcastle but Campbell preferred Portsmouth. Redknapp says he has known Campbell for years and recalls the defender visiting his house in 1994 for the 21st birthday of his son Jamie, then in the same England under-21 team as Campbell. Most striking, though, is when the manager talks of building his team around the defender.

Doubtless that was mentioned as part of his sales pitch and it is easy to imagine the impact on Campbell, who surely lost the feeling of being special to Arsenal when left out of the 2005 FA Cup final. This season Redknapp has repeatedly told Campbell, and all his squad, how fantastic they are.

Campbell does not go into detail about his final period at Arsenal but says: "Circumstances came and I had to deal with the situation - a fresh start - and Harry has looked after me and all his players. There's a good spirit here. Sometimes it can be quite tough playing football and Harry is an expert at that."

Campbell needs to be in peak condition to perform at his best, and appreciates Redknapp's management of senior players.

"He understands that when you get to this stage you don't need so much training," he says.

"You need the specifics, to tick over, but you don't need to be out there draining yourself. Some of the youngsters need more training, of course, because they want to keep improving, but if you're an experienced player you know by now what the body needs, not to train yourself out, and that's just understanding and experience. And he's a great listener."

Away from the spotlight, Campbell has found form. Errors such as the one that helped Aston Villa to equalise at Fratton Park this month would once have attracted far more attention and criticism but he is pleased with his performances.

"I'm happy," he says. "It's early days and there's a long way to go. After 30-odd games or at the end of the season that's when you've got to prove what kind of season you've had. It all comes down to at the end of the season where you finish. We want a European spot, so that's something in our minds. Being in Europe is fantastic for a club. It's a great buzz and every footballer wants to be there."

Even after Campbell played and scored in May's European Cup final his career was considered by many to be on a downward spiral. Now reaching even the Uefa Cup would confirm he was written off prematurely, and he is looking forward to continuing the journey at Arsenal.

"It's exciting," he says.

"Of course it's going to be a special game. I'm looking forward to it. I had some wonderful years there."

He hopes there is at least one more to come.

• Guardian Service

Campbell's transfers

Tottenham Hotspur 1992-2001

Won 1999 League Cup

Tottenham supporters' trust described his free-transfer move to their north London rivals as "the ultimate act of betrayal".

Arsenal 2001-2006

Won Premiership 2002, 2004, FA Cup 2002, 2003, 2005.

"I have nothing left to prove in England," he said when freed to seek a move abroad in July.

Arsene Wenger admitted it was "a big surprise" when he ended up in Portsmouth.