Is Pietersen a help or a hindrance?

The euphoria of England's historic Lord's victory lasted approximately 48 hours. Now the anxiety begins to set in with a vengeance. Which scenario, in all honesty, would suit the nation better - to be 1-0 down in the Ashes, but with Andrew Flintoff and Kevin Pietersen at the absolute peak of their powers, or to be 1-0 up as they are now, with the fitness of their star players waning by the day?

Like a Tour de France rider who's spent all his energies on a break-away from the pack, England face an agonising stretch to the line in three Tests' time at The Oval on August 24. Pietersen is already spent for the summer, the pain of his damaged Achilles forcing him into an immediate bout of surgery, while Flintoff - for all the magnificence of his Lord's performance - may not be more than a match behind him. Australia have problems of their own, of course, but with Brett Lee and Shane Watson on the upward curve of their respective fitness battles, they also have the wherewithal to finish this summer the stronger.

Pietersen's problem has been lingering ever since he withdrew from the ODI series against West Indies in May - the first international cricket he had missed for two-and-a-quarter years. All summer long, he's cut a strangely subdued figure, even during the World Twenty20 when his best performances fell short of being show-stealers. His last century in any format came during the fifth Test in Trinidad back in March, while his returns in this summer's Ashes - 153 runs at 38.25 - are some way short of the 212 runs at 70.67 he had racked up after two Tests in 2005, as well as the 268 at 67.00 he managed in defeat at Brisbane and Adelaide 18 months later.

"I'm absolutely devastated to be missing the rest of this series," said Pietersen, and there's no doubting how hard this blow will hit him (regardless of his peculiarly timed remarks about the long-term future of Test cricket). Pietersen as a competitive animal lives for the biggest stages in the world game, and now that the teams have waded through the fog of hype surrounding the 2009 Ashes, it's becoming clearer by the day just how massively competitive and compelling the remaining three games are set to be. If there was any player on either side you would have backed to seize the moment, it's the one who's just bowed to the demands of his overworked body.

Nevertheless, as Andy Flower said on Tuesday, while bracing the media for this bombshell, England can survive, and even thrive, without the big guns in their side. In the case of Flintoff, that has already been proven by the unfortunate statistics that have accompanied his recent travails - Monday's victory at Lord's was only his fourth in 24 matches since the 2005 Ashes, and his first in a live series since May 2006. With Pietersen, however, the situation is somewhat less clear. Since making his debut at Lord's, four years ago to the week, he has not missed a single one of England's 54 Tests, and in that time he's contributed to an unremarkable overall record of W18 L17 D19. Is he a help or a hindrance? Maybe the next three matches will decide.

Either way, the onus is on England's middle-order to front up in Pietersen's absence, which - as it happens - is something they have often failed to do in his presence. Ian Bell is the man who can expect the call-up to his role, and two less similar characters it is hard to imagine. Although they have performed reasonably successfully as a partnership in the past, averaging 41.80 in 32 pairings at the crease, Bell has invariably been accused of slipstreaming his more dominant team-mate, never more notably than at Lord's against South Africa last summer, when he pushed on to a career-best 199.

Bell has always been capable of such towering statistics, but his inferiority complex at England level has consumed him for four years - ever since the Australians were last here in 2005, and most particularly since the fifth Test at The Oval, the scene of the innings that transformed Pietersen into a global superstar. Before KP cut loose with the innings that secured the Ashes, Bell slunk out of the side exit with an ignominious pair, including a first-baller on that fateful final morning when it felt as if the entire future of English cricket was at stake. If Pietersen is no longer looming over his shoulder, will he have the gumption to rewrite that nugget of history?

Australia's bowlers will undoubtedly be heartened by the sight of Bell, Shane Warne's "Shermanator", striding to the crease at Edgbaston - especially if he's there in partnership with the jittery Ravi Bopara, whose over-confidence has been seized upon by the Aussies as readily as Bell's under-confidence four years earlier. But if he can bat with the uncluttered clarity that he's produced in county cricket this season, and in lower-profile Tests in previous years, it's not impossible that he will rise to the occasion. After all, he did make four half-centuries in five Tests against Australia in 2006-07, and the quality of their attack is far removed from the standards he's faced in the past.

Certainly there is no other candidate to take over Pietersen's role. Robert Key's recent double-century for Kent comes too late in a season in which his form has tailed away, while Michael Vaughan may be regretting his decision (like Graham Thorpe four years ago) to retire before the heat of battle had intensified. Bell has declared himself "desperate" to regain his England place, and having missed eight Tests in a row - his longest spell on the sidelines since his debut in 2004 - he's had time to reflect of the failings of his first coming as an England cricketer.

But at the same time, his natural diffidence is never far from the surface. Reflecting on the prospect of replacing Pietersen for the Ashes, Bell admitted to reporters at the Rose Bowl that he'd rather not, thank you. "I know this might sound strange but I want Kevin to be playing for England," he said. "He is our No. 1 batsman."

This, however, is becoming a summer that could yet be decided by the No. 2s.