Pompey were plunged back into relegation trouble as Barnsley grabbed a rare away win thanks to a fine second-half comeback at Fratton Park.
The home side had taken the lead in the 12th minute thanks to a dreadful mix-up between Barnsley goalkeeper Tony Bullock and defender Matty Appleby.
A long ball forward from Portsmouth defender Andy Awford forced Bullock to hesitate and Appleby also seemed unsure … allowing John Durnin to nip between them and slot home his third goal of the season.
It was Portsmouth's only meaningful attack of the game and it needed a fine display from their veteran goalkeeper Alan Knight to keep the scoreline down as Hendrie's men went in search of their fifth away win of the season.
Knight kept them at bay for more than an hour, until Appleby's pass sent Craig Hignett clear to smash home the equaliser from a narrow angle.
A disastrous own goal by Portsmouth captain Adrian Whitbread gave Barnsley the lead and Bruce Dyer scored a brilliant third to keep Barnsley's faint hopes of reaching the promotion play-offs alive.
Mike Sheron was responsible for much of the havoc caused in the second half as Portsmouth's fragile defence crumbled under pressure from the Barnsley front line.
In the 70th minute they were caught two against two as Sheron pushed forward and crossed from the right in search of Dyer who was arriving at the far post.
But the ball never made it to Dyer, as distraught Whitbread smashed it into the back of the net with a finish any striker would have been proud of.
Whitbread was left holding his head in his hands in dismay as Portsmouth's hopes of getting something from the game vanished.
In the 76th minute, Sheron and Dyer combined again with the former Crystal Palace striker producing a fantastic finish to extend Barnsley's lead.
Another cross from Sheron found Dyer on the edge of the area and his right-foot shot flew over Knight's head into the top left hand corner.
Referee Mark Howsey booked Appleby in the second half for a foul on Pompey winger Sammy Igoe, the only booking of the game.