With 17 games to go there can be no denying Doncaster Rovers' status as a genuine promotion contender in League One.
If their positioning in and around the top six all season is not evidence enough, their ability to consistently compete with the division's best should be.
They may have only won one of their seven matches so far against the top six sides - a 2-1 win over leaders Luton Town in September - in only one have they been roundly beaten - their defeat at Charlton Athletic.
This was their latest ding-dong battle with a third tier bigwig and they acquitted themselves superbly.
Coming at the end of a difficult week with the unpalatable Niall Mason situation, Rovers showed tremendous focus and determination to take the game to Portsmouth and hold out in the dying embers.
Though going ahead through Mallik Wilks' superb breakaway goal on the half hour may have been the moment that sparked them into life, from there they more than matched a side that had not been out of the top two since drawing with Rovers in August.
Omar Bogle's second half equaliser earned what was probably a fair share of the spoils for the hosts but Rovers had once again demonstrated where they sit in the pecking order.
The attacking qualities of this Rovers side have rarely come into question, even if they may take a little while to get going on certain occasions.
On Saturday they struggled to find their flow in the early, scrappy stages when Portsmouth's midfield press prevented fluency.
But they soon opened up, using the pace in the side to get at Pompey and cause plenty of problems, with superb passing out of midfield setting them free.
It was an alertness in the front three that brought the opening goal.
Tom Anderson crashed a clearance upfield which was not judged at all well by the high Portsmouth back line, allowing the revitalised Wilks to race clear and show tremendous composure to slot past the on-rushing Craig MacGillivray - who produced excellent stops from John Marquis and Alfie May to restrict Rovers to a single goal.
Rovers then pushed on and could easily have had a second early after the break had Marquis slid to meet a stunning low cross from Danny Andrew.
It took a mistake for Portsmouth to level, though they looked dangerous down their right for long stretches with Jamal Lowe consistently getting the better of Andrew.
Marko Marosi collided with Paul Downing as he came to meet a Ronan Curtis cross. James Vaughan drilled the loose ball towards goal but it deflected into the path of Bogle who slammed into the roof of the net.
Though Rovers had the better of the period after the equaliser, Portsmouth rallied late on and pushed the harder for the winner.
It was here where the real questions were asked of a Rovers side whose resolve late in games has been lacking in recent weeks.
But they held firm with Downing and Anderson twin colossi in the heart of defence to ensure the nerves over a late consolation never really appeared.
Marosi atoned for his part in the Portsmouth goal with a stunning one-handed stop and a couple of shows of alertness in racing off his line.
This was a demonstration of resolve needed to back up their promotion credentials.
GETTING IT RIGHT
McCann made four changes from the FA Cup win over Oldham Athletic and one glance at the team sheet showed exactly what he was after.
With Tyler Smith handed his full debut and Mallik Wilks recalled, it was a front line full of running, supported from behind by the presence of Matty Blair breaking out of midfield.
While it took Rovers time to get into the game and deal with hard pressing from Portsmouth in midfield, once they began to utilise the legs and running in attacking areas they quickly had success.
Getting at the Portsmouth back line, they found a nervy defence for the hosts who looked rattled under the pressure.
Mistakes were made, opportunities were created and for good stretches, Rovers looked the more dangerous and most likely to win.
McCann got his selection spot on, making some big calls in the process. Leaving James Coppinger on the bench is rarely an easy decision but this was a case of pace over nous and it was the correct call.
The fourth change saw Aaron Lewis make his belated debut - in place of the shamed Mason - with a superb performance to show Rovers will be in good hands if he is the option they will go with at right back for the rest of the season.
The Rovers bench was as strong as it has been for a long, long time at Fratton Park yesterday.
McCann was forced into the decision to leave Joe Wright off and, with a healthy squad, he is going to face such dilemmas over key men each and every week.
The Rovers boss could have been forgiven for whatever combination he opted for in central defence after Andy Butler's return from suspension and he kept faith with Paul Downing and Tom Anderson after their impressive partnership against Oldham.
It left Butler among the substitutes which also included Coppinger, Kieran Sadlier, Ali Crawford, Alfie May and Tommy Rowe.
Currently - and fingers are crossed over the potential rib injury suffered by top performer Ben Whiteman - Rovers are in a commanding position when it comes to strength in depth.