Manchester United have got a defensive problem that needs addressing if they are to stay in with a chance of winning the European Champions Cup.

When you play as badly as they did in the first half against Anderlecht you would hope it is a one-off in a season. But they have had two or three performances like that and we are only at the end of October.
 

We're not talking about a crisis yet. After all, they are top of the Premiership and I believe they will beat Dynamo Kiev at home to secure their place in the next round of the Champions League.

But if they repeat the performances against PSV Eindhoven and Anderlecht - and remember they had a couple of scares away to Kiev - then Sir Alex Ferguson might have to make a move into the transfer market because no matter how good your players are, once your defence starts leaking goals it affects everybody.

Ferguson is facing a dilemma. I've watched United half a dozen times this season and they have looked as solid as a rock. But while the defence appears strong enough to cope with the demands of the Premiership it does not look so secure in the Champions League, where they are meeting players and teams of a higher level.

If they played like they did against Anderlecht against one of the top European sides in the latter stages of the competition they would be out of it. As we saw against Real Madrid last season, you come under far greater pressure in the Champions League than you would do in most domestic games and if you are not rock solid then you are going to have problems.

This isn't a new development either. Last season I felt United's defence was a little suspect for two reasons. First they lacked a consistent goalkeeper, and secondly a regular partner for Jaap Stam at centre-back. Yet they still won the championship by 18 points and that tells you they have to be strong somewhere else. And United's "front six" are outstanding - just take a look at the 97 goals they scored in the Premiership.

This season they have solved the goalkeeper problem by buying Fabien Barthez, but have suffered a serious blow in losing Stam. If you removed the best defender from any team they would struggle in certain games.

But the back four they can put out is still good enough to do the business in the Premiership because United tend to just roll over teams. They don't come up against teams who throw six or seven players forward in all-out attack as they sometimes do in Europe.

It is worth noting that Roy Keane was missing against Anderlecht. He is a massive influence on the team in both directions. He plays right in front of the back four and offers them real protection. But when you have a squad of United's size and stature injuries are no longer a valid excuse.

Now could be the time for Ferguson to push Wes Brown back into action. Ferguson has been sensible with Brown, easing him back slowly after his long injury. You have to be careful with players after lengthy lay-offs. The original injury may have cleared up, but the player has been out of action for so long he can be susceptible to all sorts of other niggles and strains.

That seems to be the case with Ronny Johnsen, who was out for a similar period to Brown and seems to be picking up a number of minor injuries now. If Brown had not suffered his injury I'm sure he would be a regular in the team now. I rated him highly before his injury and from the brief appearances he's made so far this season he does not appear to have lost anything.

Ferguson has been careful not to rush him back because he knows he has a real star on his hands. The boy can be anything he wants unless the club takes risks with his fitness.

In the absence of Stam and Brown this season United's best defender has been Gary Neville, particularly when he plays centre-half. When you play at right-back you have got to be able to use the ball. That is Gary's weakness, he's not great on the ball.

But when he plays at centre-back he can use his assets. He defends well with no frills, is a great reader of the game and when he wins possession he can just play the ball simply to one of his midfield men. People say he's not big enough to be a centre-half, but he's an intelligent footballer and I don't think his height is a major problem.

Even without Stam for another couple of months, I don't think United have got a problem in the Premiership. They have just got to pray the big Dutchman is fit and back to his best by the time the Champions League resumes after its mid-winter break and that in the meantime Brown has begun to show he can fulfil his enormous potential.
A Stam-Brown partnership is one to savour. The sooner they are together the better for United.