PUZZLER ... Fabio Capello is still searching for the magic formula with England

WITH Euro 2012 just seven months away, it is absolutely vital Fabio Capello knows, more or less, his best starting line-up.

Regrettably, I fear he doesn't.

That is why I am concerned by his intention to give rookies and reserves a run-out in tonight's prestigious friendly against Spain.

OK, he's missing key players through absolutely no fault of his own.

But that's the curse of all international managers, it goes with the job.

But I suspect that even if Fabio had absolutely everybody available for selection tonight, he'd still agonise over his starting XI. Capello's selections over the years seem to have left question marks hanging over several key positions.

Not least at right-back where, in the absence of Liverpool's Glen Johnson, Manchester United centre-backs Phil Jones and Chris Smalling have filled in for recent matches — ahead of recognised right-backs, such as Kyle Walker and Micah Richards, in the squad.

And what about the centre of defence? Bolton's Gary Cahill has partnered John Terry in the last three matches, but can anybody claim with confidence they are now the Italian's first-choice pairing?

If so, where does this leave Rio Ferdinand?

It is not only at the back where there are more questions than answers.

In midfield, Jack Wilshere and Steven Gerrard would surely feature in Capello's ideal starting line-up.

But both are injured at the moment, so surely their 'understudies' would benefit from the chance to play alongside each other again, without making way for needless new faces or defenders asked to play out of position.

As a former England manager who only had friendlies to prepare for a tournament on home soil, I can tell you there comes a point when the friendlies have to stop being treated as such.

We are approaching that point, if we are not there already. Of course every party has a gatecrasher and there will inevitably be one surprise latecomer who forces his way into the squad.

But at this stage Capello should by and large know the pool of players from which he will select his group.

All matches now, including tonight's clash with Spain, should be played with a view to making his final selection by seeing how his probables and possibles perform in the system(s) he is looking to play.

That means running the rule over those who can get England off to a winning start at Euro 2012, not trying out youngsters who do not have a cat in hell's chance of being on the plane for Poland and Ukraine next summer.

Now is not the time for experimenting — it is the time for preparing. Bringing in youngsters or untried players at this stage will only muddy the waters.