The game started positively for the Reds, fielding a make-shift team, as they created a number of chances in the opening few minutes.
But Harry Redknapp's side continued to defy the odds and snatched a valuable point from a game the home side should have won.
Liverpool manager Rafael Benitez was forced to make some weighty decisions as his threadbare midfield was further depleted after Bolo Zenden's ligament injury, finally plumping for defensive stalwart Jamie Carragher.
In the first minute, the new midfield anchorman played a neat one-two with Luis Garcia, but he sent his shot fizzing wide of David James' right-hand post.
The away side could barely escape their own half in the first 20 minutes with Steven Gerrard and Carragher winning the midfield battle convincingly.
Even Sami Hyypia fancied his chances and, after being set up by Jermaine Pennant, hit a rasping 30-yard drive which dipped just over the bar.
But Liverpool's dominance was yet to produce a goal and the home crowd became restless.
Portsmouth began to find their feet and, in the 30th minute, had their first effort, albeit a poor one, with Matt Taylor hitting his drive well wide.
But soon Gerrard was back on the scene bursting from the centre of midfield in the 35th minute to latch on to a Peter Crouch knockdown - but his half-volley was always curving away from goal.
And the captain was involved again minutes later after playing the ball wide to Steve Finnan, who whipped in an inviting cross which Garcia headed into the side-netting.
Despite the home side's dominance the score remained 0-0 going into the break, much to the delight of the noisy Portsmouth support.
The Reds carried on pushing forward after half-time, with Gerrard once again hitting a powerful shot at goal which Sol Campbell bravely blocked.
The visitors stepped up their game too and the first booking came after Carragher pulled down playmaker Pedro Mendes on the centre circle after a neat turn.
A few minutes later Liverpool came mighty close to breaking the deadlock. Pennant released Gerrard in the right channel and the skipper burst down the line to fire in a dangerous low centre.
James could only palm the cross away, leading to an almighty scramble in the Portsmouth goalmouth. Garcia had two bites of the cherry but was unable to find the back of the net.
Pompey's first spell of pressure came on the hour after good work by Benjani on the right earned them a corner. The set-piece was headed out, only to reach Taylor, whose shot was bravely blocked by the Liverpool defence.
Benitez threw on veteran Robbie Flower as he searched for the elusive opener. Despite Fowler's introduction Liverpool failed to get out of first gear throughout the half and the Reds boss handed a debut to young Moroccan Nabil El Zhar to liven up the crowd.
Pompey's Nigerian striker Kanu was introduced on 82 minutes in a final attempt to unsettle the Liverpool defence with his height and skill.
Gerrard had one last chance to sneak the win for Liverpool but he flashed his 88th-minute header wide of goal.