Pompey 1 Doncaster 2 '“ Neil Allen's match report

That was eight days ago – fortunes can change so brutally.

Imposters fled the Fratton Park field on Saturday, players masquerading in masks during a cruel act of hoodwinking.

This was not authentic Pompey, the side which demolished Barnet in such devastating fashion for a fifth victory in six.

On that occasion, the Fratton faithful salivated at the free-flowing nature of their business, equipped with welcome vibrancy and a cutting edge in attacking positions.

Then a midweek trip to Blackpool beckoned.

In their place a group of pretenders strode forward, shadows stitched into football kits scrambling around to make a favourable impression.

For those who avoided witnessing that deflating let-down, there was a second outing on Saturday – and once more the Blues were unrecognisable.

Paul Cook’s side have adopted a worryingly erratic facade within the past week, particularly in terms of the defensive part of the game.

The result was criminal generosity towards a promotion rival who snatched the helping hand on offer to depart Fratton Park with three points.

No question about it, Doncaster Rovers will remain serious contenders during the campaign’s progression, already ranking as the best opposition faced so far.

With the hard-running John Marquis and free-scoring Andy Williams serving as partners in attack, they certainly don’t require any assistance in efforts to strengthen a hold on the top three.

Yet that is precisely what they received as generous Blues defending ensured this battle was effectively settled as early as the 34th minute.

Cook’s troops recorded four clean sheets in their opening six League Two fixtures – they have now conceded nine times in the subsequent five matches.

Of those, five have occurred during the past two games – desperately poor showings against Blackpool and now Doncaster within 96 hours of each other.

Most alarming of all, every single one of those five goals have been influenced by substandard defending from a side supposedly well-equipped to win promotion.

Bloomfield Road witnessed a goalkeeping error from a free-kick and two incidents of being caught in possession in positions dangerously close to goal.

Disturbingly, the manner of those shipped on Saturday was even worse – with added ignominy of materialising at Fratton Park, a previously undefeated venue this season.

Within eight days Pompey have discovered two defeats and a defensive inadequacy never previously hinted during the early stages of the season.

Rightly, fans are concerned. At the highest of heights, suddenly a weak underbelly has been glimpsed.

The outcome of four defeats in the opening 11 League Two matches is anything but the strut of a team confident of winning promotion.

To add to the exasperation, Cook opted to recall Matt Clarke for the visit of Darren Ferguson’s side, a credible decision designed to bolster his rearguard.

Central defender Tom Davies’ uncertain display at Blackpool cost him his place, representing the only change to the team.

So for Clarke a first league appearance since April, his absence influenced by a persistent groin problem and then the need to come up to speed.

Having performed so impressively while on loan from Ipswich last season, few would have criticised his inclusion against Rovers.

Yet the 20-year-old couldn’t cure a defence which has suddenly developed a tendency to creak and buckle in recent fixtures.

Elsewhere it was the same again, fans’ favourite Conor Chaplin retaining his place in attack for a third match in a week, while Kal Naismith continued on the left.

Their inclusion had helped instigate that Barnet landslide which seems so agonisingly far away now.

For Saturday, Cook had fine-tuned his team, he resisted the urge for more changes to the side which failed so badly at Blackpool, he retained faith in the bulk of the players to have previously recorded four successive victories.

And the result was a 2-1 defeat largely self-inflicted.

Granted, goalscorer Carl Baker struck the bar, while Gary Roberts’ header was cleared off the line, both arriving in the second half.

Yet the mountain created by two goals in the opening 34 minutes was insurmountable, especially against a side possessing the qualities of Doncaster.

Pompey dug their first hole on seven minutes when Andy Butler’s lump down the left-hand channel sent former loanee John Marquis galloping away.

Clarke was matching the striker stride-for-stride as they approached the penalty area, only for David Forde to suddenly spring off his line.

The veteran keeper raced out of his box only to be effortlessly sidestepped by Marquis, providing an empty net to be struck.

It was flawed judgement from Forde and for the second game running must take responsibility for the opening goal conceded.

In fairness, there was little he could do with the second, emanating from a delivery deep in Doncaster’s half.

With Roberts’ clip on Joe Wright having given away a free-kick, the ball was lofted forward and flicked on unchallenged by Butler.

Neither Christian Burgess or Clarke were close enough to Williams, who simply swivelled to divert the ball past Forde from close range.

However, the deficit was reduced on 42 minutes after Gareth Evans had delivered a cross from the right to the far post.

It appeared to be running out of play, only for Jordan Houghton to panic and hook the ball back into danger, where Baker crashed a shot into the roof of the net.

Pompey bossed the second half, with Baker diverting substitute Milan Lalkovic’s delivery from the left onto the bar.

Then Butler backheeled Roberts’ header off the line, following man-of-the-match Baker’s measured cross from the right.

They were moments which left Cook to reflect on genuine opportunities to have snatched the point he felt his team warranted.

Yet that would have represented nothing more than papering over the defensive cracks growing by the week.