Norwich were forced to hold on desperately for the three points as relegation-haunted Portsmouth came within an ace of staging a fight-back.
The Canaries looked set for a comfortable victory as a Craig Fleming header and a Iwan Roberts penalty put them two up inside 24 minutes.
But the managerless visitors came storming back and deserved more than just Lee Bradbury's 58th minute goal for their efforts as they totally dominated the second period.
Norwich looked well in control early on and veteran keeper Alan Knight had already made one good stop to foil Darel Russell when he was beaten on nine minutes.
The alert Chris Llewellyn chased after a mishit pass before sending over a beautiful in-swinging cross which Fleming powered home from close range for his second goal of the season.
The Canaries continued to dominate and it came as no surprise when they made it two 16 minutes later with Roberts' 11th of the season.
Midfielder Stefani Miglioranzi was penalised for fouling Darren Kenton in the box and Roberts stepped up to convert Norwich's first penalty of the season, sending Knight the wrong way from the spot.
Pompey looked dead and buried at that stage but for the next 30 minutes they totally dominated proceedings and gave a hint of what was to come after the break. On 37 minutes when Miglioranzi's volley clipped the crossbar.
The Canaries simply didn't know what had hit them after the re-start as the visitors carved out chance after chance. The best came after 55 minutes when Andy Marshall produced an excellent save to deny the impressive Sammy Igoe after the little midfielder had been put clean through.
It seemed for a while as though the visitors were destined not to score but three minutes later they finally made the breakthrough as Matthew Robinson's run and shot caused chaos in the Norwich defence and Bradbury stepped up to blast home the loose ball from just outside the six-yard box.
Curiously, Portsmouth were never such a threat after reducing the arrears and Norwich went close to making it 3-1 ten minutes from time when Fleming's header clipped the bar.
But the battling visitors kept going right to the end and almost made it 2-2 in injury time when a frantic goalmouth scramble ended with Miglioranzi's scuffed shot going just wide.
Norwich are now just three points off the play-off zone but on this evidence have a lot of work to do if they are to become genuine promotion contenders.
Portsmouth, meanwhile, should have few problems avoiding the drop if they maintain the battling qualities shown today.