Sam Allardyce believes tightening Sunderland's fragile defence is key to transforming their fortunes.

Allardyce was named manager at the Stadium of Light on Saturday following Dick Advocaat's decision to quit and return to the Netherlands and he inherits a Sunderland team without a win in the first eight Premier League games this season.

Key to their struggles has been a porous backline that has shipped 18 goals in eight league games and former centre-half Allardyce is hoping to improve that woeful record.

He told the club's official website: "I have come across challenges like this before and managed to pull clubs out of the relegation zone and hopefully I can do that again. The challenge is a big one but I'm a big man and I like a challenge.

"I don't know exactly how good we are as a squad but I know a lot of the players. I feel that if I improve the defensive record, prioritise that first, we can start winning football matches.

"I know it's a difficult job but like everything else you believe in yourself as a manager. I've got to believe that when I get into the players I can make them better and get out of the position we're in.

"Getting settled in is the hardest part as the season is underway and each game comes around quickly. We have to prepare for the first game at West Brom and I have to install some confidence in the players so we can go one better than we did against West Ham."

Allardyce's style of football has been criticised over the years during spells at Bolton, Newcastle, Blackburn and West Ham but he is hoping to entertain the supporters as well as drag the club out of the relegation zone.

"We're averaging over 40,000 and the fans haven't had a lot to cheer. I need to give them some entertainment at home and, more importantly, winning more matches if we want to get out of this problem," he added.

"It's about improving the players that are here at the moment and improving the squad overall. Behind the scenes, it's about getting everyone pulling in the same direction.

"The lads appear to be in a relatively positive frame of mind and I need to work out how best to get them to play, individually and collectively."