Pompey threw away a two-goal lead to be held to a 2-2 draw at Bristol Rovers.
A stoppage-time own goal from keeper Craig MacGillivray meant the Blues missed out on successive League One victories at a rain-soaked Memorial Stadium.
The visitors were well on their way to three points, after goals from Gareth Evans and Ronan Curtis either side of half-time put them in control.
But Alex Rodman gave Rovers a lifeline before McCrorie turned into his own net in the dying embers.
Kenny Jackett made one change from Tuesday’s 1-0 win over Lincoln, with Curtis replacing Marcus Harness in a left-wing role.
Ben Close should have done better with the first sight on goal in five minutes. Ryan Williams cut the ball back but the midfielder scuffed his shot.
But Pompey were to be handed a golden opportunity to break the deadlock in the ninth minute. Evans’ cross was flicked on by Sean Raggett and John Marquis received a nudge in the back from Luke Leahy.
The referee immediately pointed to the penalty spot and Evans rifled home the effort to give the Blues the lead.
The fans’ favourite continued to be at the heart of things when he released Marquis through on goal in the 13th minute but home keeper Ansse Jaakkola did well to hold the striker’s shot.
Former Fratton triallist Victor Adeboyejo started for Rovers – and went close to equaliser when he deflected shot went narrowly off target.
The the Blues rued three big opportunities to extend their advantage. In the 21st minute Curtis set Marquis free on goal but Abu Ogogo tracked back to block his effort.
From the set-piece, Christian Burgess’ header was kept out by Jaakkola before Raggett’s aerial effort from Lee Brown’s delivery forced a fine save from the Gas stopper.
The home side made a decent response, with Ed Upson’s 25-yarder taking a nick off the lunging leg of Tom Naylor to just go wide.
In the 36th minute Curtis’ cross almost caught Jaakkola off line and he was forced to backpeddle and tip away with the ball heading for the top corner.
The Blues were given an early scare within the opening stages of the second half when Leahy’s cross cannoned off McCrorie. The home fans wanted a penalty but the referee wasn't interested.
After a spell of pressure from the Gas, an Evans free-kick in the 61st minute caused all sorts of panic but Rovers managed to clear.
And Pompey doubled their lead at just the right time with 20 minutes remaining. Marquis’ drilled cross intelligently picked out Curtis and he headed home with aplomb from close range.
Jackett’s men threatened to add a third when Williams got to the byline and his low cross was just cut out with Marquis lurking in behind.
But it was Rovers who’d score the next goal with 12 minutes remaining. Pompey failed to clear a free-kick and Rodman’s shot on the spin found the bottom corner.
That made for a nervy ending, with Rodman again going close after the Blues’ couldn’t get rid of another set-piece.
And in the 93rd minute Graham Coughlan’s men had their leveller.
McCrorie tried to sweep away a corner but got his clearance all wrong and the ball went into the net via the crossbar and MacGillivray.
It’ll undoubtedly be seen as two points dropped as Pompey remain 16th in the table.