Yakubu Ayegbeni's last-gasp goal gave Portsmouth a narrow win over 10-man Blackpool, who had Gareth Evans sent off in stoppage time.
The Nigerian bundled the ball over the line to send the home side into the fourth round of the FA Cup.
Pompey had gone ahead in the first half when Sebastien Schemmel crouched to head home Matthew Taylor's cross.
Scott Taylor drew Blackpool level with a smart finish just before the break.
The much travelled Taylor claimed his 22nd goal of the season when he picked up Martin Bullock's pass and guided his shot past Harald Wapenaar.
Harry Redknapp's side were given early warning of the excellent understanding between Bullock and Taylor, who scored a hat-trick against Oldham in the
previous round as Blackpool quickly settled.
Bullock's pass picked out Taylor, who was thwarted by Harald Wapenaar's smart dash from his line.
A wonderful piece of skill from Richard Wellens also sent Simon Grayson clear, but Matthew Taylor diligently tracked back to concede the corner.
36 mins: Schemmel's header gives Pompey the lead
43 mins: Scott Taylor equalises for Blackpool
61 mins: Burton hits the woodwork twice in quick succession
90 mins: Yakubu's scrambled effort wins the game for Pompey
Just past the half-hour Wapenaar had to athletically tip Gareth Evans' dipping cross over the bar.
A period of sustained Portsmouth pressure ensued after Pool keeper Lee Jones made a fine save from Yakubu.
A Matthew Taylor shot also caused pandemonium in the Blackpool penalty area as the ball richocheted around the box like a pinball machine.
Richard Hughes then unleashed a fierce shot which Jones clutched to his chest, while Steve Davis put in a well-timed tackle to deflect Yakubu's shot to safety.
Daniel Coid put in an even better last-ditch tackle to thwart Alexei Smertin, just as the Russian was primed to shoot.
But on 36 minutes Portsmouth went ahead as Matthew Taylor delivered a cross from the left and Schemmel ghosted in from the right to nod the ball past Jones.
Up to that point Blackpool had displayed plenty of elegance on the ball but too many of their attacks had petered out when they reached the Portsmouth area.
But on 43 minutes all that changed when Bullock surged in from the right and threaded the ball through to Scott Taylor, who turned Arjan de Zeeuw before firing his shot past Wapenaar.
After the restart, Portsmouth upped the attacking ante and Deon Burton, who had had a quiet opening half, went close with a succession of chances.
The former Derby striker first sent a curling shot narrowly over the bar and then drew a fine save from Jones after good work by Sheringham and Smertin.
From a Matthew Taylor corner, Burron also hit the bar twice with a couple of scrambled shots.
With the game heading for a replay, Yakubu forced the ball over the line after Sheringham made a trademark near-post run to glance a header which Jones was unable to hold.
Blackpool's misery was completed by Evan's dismissal as he picked up a second yellow card.
Portsmouth: Wapenaar, Zivkovic, Taylor, Stefanovic, De Zeeuw,
Schemmel, Smertin, Hughes, Sheringham, Burton,
Yakubu (Robinson 90).
Subs Not Used: Srnicek, Cooper, Pulis, Hunt.
Booked: Hughes, Yakubu.
Blackpool: Jones, Grayson, Evans, Flynn, Davis, Bullock,
Wellens (Clarke 79), Coid, Hilton, Murphy, Taylor (Johnson 90).
Subs Not Used: Barnes, Sheron, McMahon.
Sent Off: Evans (90).
Booked: Taylor, Evans.
Referee: S Dunn (Gloucestershire).