Phil Smith's verdict: Making sense of Sunderland's first setback and the questions that Portsmouth raised for Black Cats

A fierce low drive was well stopped by Lee Burge, but by now the game up was up.

Portsmouth were a man to the good, Luke O'Nien sent off after being worn down by this type of counter-attack from the visiting forward line.

There were despairing looks and hands on hips, clear signs of fatigue and of defeat.

Having gone to three up front, the balance of Sunderland's side had been irreversibly altered and there would be no turning the tide.

It wouldn't be Burge's last action, either.

Essentially limited to a watching brief in recent weeks, this was his busiest afternoon of the season, a reflection of how Portsmouth were the first side to truly find holes in Sunderland's hitherto resilient system.

Portsmouth mustered 11 shots when the average against Sunderland this season is six.

Even more notable was the quality of those opportunities.

So far, only around 25% of those shots Sunderland have conceded have been on target, a reflection of the way they have forced the opposition into attempting the low-percentage options. On Saturday, 77% of Portsmouth's efforts were on target.

The question for Sunderland, clearly, is whether this was the consequence of a rare off day, or signs of a more concerning fallibility.

The truth, as ever, lies somewhere in the middle.

Perhaps the clearest conclusion to draw from this contest was that Portsmouth will, without any doubt, be a close promotion contender for the Black Cats this year.

They came into the contest on the back of an indifferent start to the season, with pressure building on Kenny Jackett.

Those on Wearside, though, were not fooled.

Contests between these two are always settled by narrow margins. They are always tense, bruising encounters and even if the lack of fans took away some of that edge, this was a high-quality League One contest.

Both sides are now tracking around the two points-per-game mark and anyone who finishes above them will, you suspect, win promotion.

Phil Parkinson insisted afterwards that there would no be overreaction to this first league defeat.

Portsmouth, he said, had managed to do to them what they have done to many of their opponents so far this season.

By that, he meant force mistakes through their pressing, before breaking quickly when winning possession.

Pompey striker John Marquis explained after the game that they had analysed Sunderland's shape and noted the way that they can leave themselves exposed in their preferred system, one which pushes the wing-backs right up the pitch and encourages the central midfielders to break forward.

Marquis and his fellow forward players thrived in those gaps.

Sunderland, though, were the architects of their own downfall.

The opener came perhaps partially through overcommitting players, but also through a rare lapse in concentration. Grant Leadbitter's crossfield pass bounced over Denver Hume, and no one in a red-and-white shirt reacted quickly enough to the danger this created.

Portsmouth took the throw-in quickly and drove into space, pulling Sunderland out of their usual structure and creating the overlap for Harness, who was a thorn in the Sunderland side throughout.

The second goal came from a rare error from Grant Leadbitter, outstanding throughout the season so far. Sunderland lost possession in a dangerous are and again, it allowed Portsmouth to capitalise on the kind of space we have rarely seen the Black Cats give up this season.

Parkinson pointed to a second-half revival as a sign that this defeat was not the consequence of a major structural issue, and there was some credence in that.

Where they had been passive in the first half, they stepped up the pitch and were able to get their key attacking players in more dangerous positions.

At times, the visiting side looked unable to cope with Hume in particular, who drove into advanced areas and beat players with regularity.

To their credit, Portsmouth stood firm and when the flow of the game was inevitably disrupted by injury and substitution, they used that opportunity to build their way back into the game.

When the third goal came, it was fully deserved and it did underline one of the key questions for Sunderland.

Parkinson had opted to persist with Luke O'Nien on the left of the back three, citing his 'magnificent' recent performances. For O'Nien and Gooch on the right, though, this was a significant step up in terms of the quality of opponent.

The Sunderland camp suggested O'Nien made no contact with Ryan Williams for the penalty, yet there was no mistaking the passage of play reflected a tiredness in decision making that comes at the end of challenging afternoons.

It would not be a surprise if one of the consequences of this first defeat was a return to a more familiar back five.

Most concerning of all was that despite that early second-half pressure, the Black Cats finished the contest with just one shot on goal.

If the biggest concern for many so far this season is that Sunderland have looked like a top-two side in defence but not so much in attack, this was an afternoon that presented more evidence to that effect.

Ultimately Parkinson’s substitutions did little to alter that toothlessness as Sunderland fell deservedly short.

A knock, and a setback, without a doubt.

Sunderland's excellent start to the season had built hope that this would be an afternoon where they underlined their progression with a commanding display.

It was not to be.

Yet in this most hectic of schedules, opportuntiy knocks quickly and two games in five days gives Parkinson the opportunity to show that this was merely a day when Sunderland collectively fell short of their best level.

One thing is for certain, he won’t be altering course, and has laid down the gauntlet to his players to vindicate that quickly.

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