FABRICIO Coloccini has given Newcastle United a serious injury scare ahead of this afternoon's trip to Manchester United.

The Argentine, arguably the Magpies' best player this season, is believed to have suffered a back spasm which is threatening to rule him out of the Old Trafford game.

And it is of sufficient concern for manager Alan Pardew to call up Hungarian youngster Tamas Kadar, who is on stand-by to face Wayne Rooney and Co.

With Mike Williamson already ruled out, Pardew has always been fearful of an injury being picked up by either Coloccini or Steven Taylor.

And it is understood that the manager was worried enough about Coloccini's problem to rush a back specialist to Manchester last night to give his captain a closer look.

Although Coloccini has not been ruled out of the match, there is a real threat that Newcastle will have to field a different back four for the first time in the Premier League this season.

Kadar spent the majority of last season recovering from injury and after suffering another set-back in pre-season, the defender has had to fight his way back to fitness.

Since arriving in August 2009, the defender has been regarded as a top prospect, but a nightmare year has seen the 21-year-old fall out of the picture at St James' Park.

He is a regular in the reserves and it is understood that the Magpies' would have been receptive to loan offers before Thursday's Football League loan deadline.