United today confirmed Coloccini has completed his £9.5m move from Spanish side Deportivo la Coruna - a club record for a defender.

The Argentine defender is expected to be in the squad for the Manchester United game, and Keegan said he has not decided whether he will play a part against Sir Alex Ferguson's team.

Keegan said: "It's definitely a possibility.

"I haven't spoken to him about it, but I know he wants to play. I haven't decided yet.

"He's an absolute quality player who's played at the top level.

"He's played with some great players and is completely at ease with them.

"He's my type of defender - he doesn't just defend. He's very comfortable in other positions, and that's a bonus.

"He can use the ball, play in both centre-half positions and at full-back, and in central midfield. That's why he's a fantastic acquisition."

Coloccini was unveiled to the media this afternoon at United's Benton training ground.

He said: "This is a new stage for me in my life and career.

"It's exciting that the first game is at Old Trafford, but even more exciting that I might play my first match for Newcastle in the Premier League."