When the stakes are at their highest, you need to rely on what you trust. That is why Kevin Keegan is prepared to push it to the limit over Alan Shearer here tonight.

Were he any other player - with the possible exception of Tony Adams - Shearer's need for an anti-inflammatory injection below his left knee would rule him out of contention against Portugal.

But Keegan feels no other striker is capable of delivering the goals that England need, that Shearer alone represents the embodiment of his brand of spirit.

Although Shearer cannot be 100 per cent - he has not trained properly for the past month with the tendinitis problem - he is willing and able to shoulder the responsibility of leadership.

The Newcastle man knows the stakes are high for both himself and Keegan. It is a high-risk strategy, with the dangers of a breakdown all too obvious.

If either Shearer or Keegan fail, the self-inflicted nature of the wound will make the fall-out all the more bitter.

But all the discussion over Shearer and his role overshadows the real gamble that Keegan is taking tonight.

In selecting Steve McManaman rather than Dennis Wise to play on the left side of a four-man midfield, in front of Phil Neville, Keegan has reverted to attacking type just when it appeared he had learned to adopt caution.

Keegan believes McManaman's season at Real Madrid has given him the confidence to run at the Portuguese defence and force Luis Figo to work back to help out.

Theoretically it sounds fine. If McManaman can finally break free of the mental shackles that have restricted him on previous England appearances and reproduce his recent Real form, then Keegan's game-plan will have the opportunity to blossom.

A floating, marauding McManaman would guarantee space elsewhere, opening up the passing avenues to the other flank, where David Beckham should get the opportunities to work his magic, or seduce defenders into conceding the free kicks that Keegan believes will lead to goals.

But the last time England played 4-4-2 against a major nation, when Brazil came to Wembley two weeks ago, Keegan's side spent the entire second half watching the South Americans play keep-ball.

Portugal are not Brazil. Yet in terms of temperament, movement and natural ability they are the nearest European equivalent, a team with the ability to hit on the counter with devastating effect.

If England are unable to keep hold of possession, they run the risk of being opened up down that problem left flank, where Figo and Secretario will relish the prospect of the likely hole behind McManaman and in front of the potentially exposed Phil Neville.

In addition, Paul Scholes' vital ability to steal forward beyond the strikers could be hampered - as it was against Brazil - by the defensive demands on him, effectively muzzling one of England's biggest weapons, while Paul Ince will be pulled across.

It represents a massive all or-nothing punt and Keegan effectively admitted last night that his natural instincts had taken over. He said: 'If we look at Portugal and just think about a team to stop them, we're going to be on the back foot from the first minute.

'It's not only my way. I think this team has got the balance not only to defend well against the world-class players but to cause an awful lot of problems. We've got goals in us.

'A lot of my time is taken up trying to think adventurously. That's the sort of person I am.'

The manager added: 'I sense the players feel that they've got the opportunity to make this a memorable three weeks. The players are ready. We want to go and perform and make the country proud of us.'

Keegan recognises the menace of Figo and said of his tussle with Beckham: 'We'll see the finest No.7s in world football.' But there is more to it than that, although Beckham's set-piece delivery appears ever more crucial.

Real Sociedad's lively Ricardo Sa Pinto will be missing through his own knee problem, but Keegan added: 'Their strength is their invention, with Rui Costa and Figo.'

It was the Fiorentina man, rather than the Barcelona raider, who taxed the mind of Adams. 'I think they snap into action in our third,' warned the defender, who tasted Wembley defeat against both in this season's Champions League.

'They like to come forward. Rui Costa is the man. He can open you up if he's not looked after. Their system doesn't change. But don't build them up.

'Sometimes it's your moment, your time to win it. You can get players who have been out with injuries coming back and it all clicks into place in a two-week period. I think it could be our time.'

Adams and his tub-thumping dressing-room oratory with its Shakespearian overtones reflects the bubbling confidence emanating from Keegan and his players. But history signals the scale of the mountain England must conquer.

In five previous attempts, they have still to record their first victory in the opening match of a European Championship campaign, with three draws and two defeats.

Even more alarming is the fact that England have never won a 'live' match in this tournament off home soil. The only victories in 11 games before Euro 96 came in the third-place play-off against the Soviet Union in 1968, and against Spain in Italy in the final group game of 1980, by which time Ron Greenwood's side - including captain Keegan - had already been eliminated.

They are stark statistics which put expectations of Keegan's side into a proper context.

That does not mean to say that England are being unrealistic. With Beckham, Michael Owen, Scholes and McManaman, there is the potential for the unexpected, while Shearer - we must take his word on his fitness - Ince and Adams represent the formidable and experienced spine.

The Portuguese are more likely to be nervous, for all their claims of being the underdogs.

But this is Keegan's hour and a half of destiny. If he has got it right, in going with Shearer, in placing such faith in McManaman, he will be vindicated. If wrong, he will be castigated. As he accepted: 'We will meet for alibis afterwards.'

When it comes to spotlights, it is fitting that the harshest glare comes in a stadium built and powered by Philips. A win would make everything seem more possible. But England cannot afford defeat. It is as simple as that. The verdict will be unequivocal.