GRAEME Souness last night revealed that Jean-Alain Boumsong is joining Newcastle vowing to become the best centre-half in the Premiership.

The France international, who spent yesterday on Tyneside passing his medical, has become Newcastle's second winter signing after agreeing a five-and-a-half-year deal with the club.

Weeks of intense negotiations ended on Thursday night, with Rangers agreeing to accept Freddy Shepherd's offer of £8m for a player they signed for nothing from French side Auxerre in the summer.

The 25-year-old has made just 28 appearances for Rangers, but they have been enough to convince Souness that he is the man to solve a defensive crisis that has seen the Magpies concede 38 Premiership goals this season.

With former Chelsea defender Celestine Babayaro also having agreed a three-and-a-half-year deal this week, the United boss has wasted no time in bolstering the defensive ranks.

While Boumsong may be a virtual unknown south of Hadrian's Wall, the cultured defender is confident he will make a major impact on the Premiership.

John Terry, Sol Campbell and Rio Ferdinand have taken all the defensive honours going this season, but Souness is confident his latest addition is every bit as good as that talented trio.

"I think Jean-Alain expects to be up there with anyone you'd care to name in the Premiership," said the Newcastle manager, who also confirmed he is continuing to track Manchester City defender Sylvain Distin as he attempts to make one more signing this month.

"He's determined to prove himself as one of the best defenders in this league. He wants to be right at the very top, but he won't be properly tested until he plays in the Premiership.

"The stories that are coming out of France suggest that he's going to be their first-choice centre-back for a long time to come. I'd love to think he was going to be here for a long time and be an outstanding defender for this club.

"We see Jean-Alain as a big influence at the club, both short and long-term. He's quick, he's strong and he's good on the ball. He's a young man who has a great desire to be the best.

"He's a communicator on the pitch and you can never have enough of them.

"We've been lacking people who are talkers and he will certainly help us in that department. I think the supporters will enjoy watching him play."

Having managed Rangers for five years in the 1980s and '90s, Souness' Scottish contacts undoubtedly helped to lure Boumsong to St James' Park.

But, while the former Scotland international continues to enjoy a close relationship with Rangers chairman David Murray, it was actually someone from the other side of the Glasgow divide who persuaded him he was making the right move.

Celtic striker John Hartson has had three physical tussles with Boumsong this season and, while the Wales international is one of the toughest strikers in the game, he did not relish locking horns with Newcastle's latest signing.

"We have our Welsh contacts who have been speaking to John Hartson," revealed Souness. "And he's told them that he didn't enjoy playing against Boumsong.

"Along with Alan Shearer, John Hartson is probably the last of your big up and at them centre-forwards. He's a real handful on the day, but Jean-Alain has dealt with that, and the threat posed by Chris Sutton.

"I'm hoping he'll settle quickly because he's just coming from Scotland. British football is more intense than it is on the continent - it always has been and our supporters will dictate that it stays that way.

"But I would hope that Jean-Alain settles in straightaway, because he's played against Celtic several times and he knows what that intensity's all about."

Despite the transfer window opening today, FA rulings dictate that neither Boumsong nor Babayaro can be officially registered as Newcastle players until Tuesday.

The duo are expected to make their United bow in next weekend's FA Cup third-round tie with Yeading. With games against Birmingham and West Brom to come before then, the rest of United's defenders are effectively playing for their futures this weekend.

Titus Bramble and Aaron Hughes are expected to continue at centre-half when Steve Bruce's Birmingham visit Tyneside this afternoon but, with Andy O'Brien also fit following a virus, three players will be tussling for one place once Boumsong becomes available.

Souness has insisted that he has not drawn a line through anyone's name - especially with Boumsong being ineligible for the UEFA Cup - but the Scot must secretly be hoping this week's events focus a few minds.

Birmingham have won their last four league games, as opposed to Newcastle who have failed to win nine of their last ten. And while Wednesday's performance against Arsenal raised morale, United's fans will demand their side begin 2005 by ending a run of seven home games without a victory.

Souness can at least call upon the services of Alan Shearer following a thigh injury, and the United skipper is expected to go straight into the starting line-up.

"We know what Alan's all about," said Souness. "He's a man that you'd want with you in a battle and a man who you'd want with you in a difficult time.

"Apart from his goals and his 90 minutes on a Saturday, we've missed him when he's been out of the group.

"He lifts training by his attitude and I think people in the dressing room get confidence from having him around."

Stephen Carr also returns to the squad following his knee problem, although the former Tottenham defender is unlikely to start given that he has not played since November 14.