Four different players were on target for Pompey Women, but they still suffered late heartache at Watford.
It looked like they had done enough to rescue a point after battling back from 4-1 behind, with Shannon Albuery, Rachel Panting, Becki Bath and Katie James all netting.
But Helen Ward – Wales’ all-time record scorer – struck with the last kick of the game to secure victory for the Hornets.
Blues boss Jay Sadler handed a full debut to Bath for the contest, which took place at the Hertfordshire FA County Ground.
And it was the visitors who made the brighter start to the game, applying plenty of pressure in the early stages.
The first proper chance came when James crossed for Bekah Tonks, who saw her header fly agonisingly wide.
Pompey were looking to record a fourth successive win and their dominance continued as the first half progressed, with Panting and James both having efforts saved.
But it was their opponents who took the lead on 21 minutes, as Adekite Fatuga-Dada’s ball across the face of goal was tapped home by Ward.
And the hosts soon doubled their advantage after Danielle Scanlon raced through and as she tried to round Hannah Haughton, Danielle Rowe inadvertently turned the ball into her own net.
Pompey did not let their heads drop, however, and when James combined with Eilidh Currie on the left, an eventual effort from Jade Bradley was saved.
Shannon Albuery then played an inch-perfect pass for Bath late in the first half and she forced Weronika Baranowska into a crucial double stop.
But their persistence paid off in the end, as ALBUERY stole possession, raced clear and slotted the ball into the bottom corner.
Half Time: Watford 2 Pompey 1
Despite that lifeline, it was Watford who emerged fastest from the blocks once the action restarted after the break.
Ward was again on target for the hosts, cutting inside before curling an effort past Haughton and into the net.
They soon had a three-goal cushion, with Ward turning provider by sending the ball across the box for Leanne Bell to convert.
But Pompey then embarked on an incredible comeback, with James going close by hitting a shot that cannoned back off the post.
And James was then fouled in the box, with PANTING confidently hitting the resulting penalty right into the bottom corner.
It was the Blues’ turn to score goals in quick succession, with Albuery sending the ball back for BATH to open her account for the club.
The tide was turning, as Sadler’s side searched for an equaliser, with Baranowska getting down well to deny Albuery.
Haughton, meanwhile, was enjoying a quiet period of the match, but had to keep her concentration to deny Ward.
And Pompey were level in the 90th minute, with JAMES firing home from inside the box to make it 4-4.
But it was the Hornets who had the final say, as Ward converted a low cross from Fatuga-Dada in stoppage-time.
There was not enough time for the Blues to reply, with the final whistle blowing seconds later to ensure it would be a cruel defeat for the visitors.
Pompey: Haughton; Kirby (Perkins 85), Southgate (c), Tonks, Currie; Rowe, Bradley; James, Bath, Panting; Albuery
Subs not used: Burns, Younger, May
Next up for Pompey Women is a midweek National League clash with Chichester, who visit the PMC Stadium on Wednesday, February 13 (7.45pm kick-off).
Football can be the most cruel sport in the world sometimes. Gutted doesn’t even come close. Unreal fight to come back from 4-1 down but only have ourselves to blame in the end 💔 https://t.co/TmzCQHTTVQ— Danielle Rowe (@DanielleRowe96) February 10, 2019