By Alan Hansen BBC Sport football expert

Ruud van Nistelrooy's winner for Manchester United against Southampton has raised the grim spectre of another alteration to the offside rule.

Gordon Strachan was rightly angry - when it comes to offside the lawmakers must keep it simple

Van Nistelrooy was, according to the lawmakers, deemed to be "passive" by the assistant referee when a free-kick was taken, despite standing in an offside position in the six-yard area.

Then, when the ball was played back into the box after the free-kick was partially cleared, we were apparently into "second phase" play, so he can score providing he has returned to an onside position.

This rule is absolute nonsense. What is passive or active? What is second phase? Do me a favour.

I just shake my head now and cannot believe what is going on. It is a recipe for confusion.

This basic rule should apply to the offside laws - namely that simple is good.

When things are simple more people understand and less people get things wrong.

Clarity should be the keyword and it should just be the case that if you are in an offside position you are offside. End of story.

What we have got here, and what justifiably angered Gordon Strachan, is a mess.

Nobody can understand the rules. Teams don't know whether they are coming or going.

It must be a nightmare playing in a back four and I dread to think of all the thoughts going through a linesman's head as the ball comes into the penalty area.

This rule is absolute nonsense. What is passive or active? What is second phase? Alan Hansen

It's causing controversy now, but just wait until the big boys' prizes are handed out or a relegation battle has been affected.

We are trying to stop supporters getting over-heated and cooling trouble for managers and players, but rules such as this encourage it.

Van Nistelrooy was in the middle of the penalty area and deemed to be passive, but I'll tell you this.

If you stuck another three in there who were also deemed to be "passive" the flag would go up right away. I would bet you all the money you like on that.

There are serious consequences for football because of this.

There is an art to pushing out as a defence. You are taking a chance by leaving space behind you, but teams won't take that chance if they could find six players in that space who could be ruled offside.

You will now get teams defending deeper and deeper and you are not going to have a game. Teams will be scared to come out and defend higher up the pitch.

Throw in the fact that the linesman does not have a great picture of who is passive or active looking across the line, plus the referee may also have problems looking from 40 yards away, and I think you could have problems on your hands.

As I said, people should either be offside or not. Let's cut out passive and active, first and second phase and just have players who are offside or onside.