Nico Kranjcar's late second offered a welcome respite from the perils of the Premier League for manager Tony Adams, who has not enjoyed the best of starts to management at the top, but at least he was able to extend the legacy achieved by former manager Harry Redknapp last May. He may remind him of that when the pair meet at White Hart Lane on Sunday.
Adams has enjoyed previous success in the competition, lifting the trophy three times during his halcyon days with Arsenal, in 1993, 1998 and 2002. And the former England defender began his managerial career in the competition, leading Wycombe to a 4-1 win over Swindon six years ago.
Winning, though, has not come easy for Adams, who went into the tie having secured only three victories from 15 outings since being confirmed as the successor to Harry Redknapp, the man who guided Portsmouth to their first major silverware in 69 years when they beat Cardiff in last May's Wembley final.
Eight months after winning the trophy, Portsmouth continued their defence – having been held to a goalless draw in the original tie – with only six of the players who featured at Wembley.
Before the game, ballboys paraded around Ashton Gate with a banner proclaiming the simple words: 'Always Believe' while the home fans belted out the Wurzels' popular unofficial club anthem 'Drink Up Thy Zider'.
Neither side has been drunk on success this season, though Portsmouth went into the game having gone an impressive 535 minutes without conceding a goal in the competition.
And Crouch had a chance to put the visitors ahead when a threaded ball, from Niko Kranjcar fell invitingly, but he sent it flying towards the Clifton Suspension Bridge.
City responded when Marvin Elliott forced a fine save out of David James.
David Nugent and Glen Johnson wasted further chances for Portsmouth while Nicky
Maynard's intelligent lob gave the holders a scare, dropping onto the top netting, before Portsmouth's David Nugent struck a post.
City should have had a penalty when Crouch clearly handled as he attempted to clear a cross, but from that incident Portsmouth broke forward and the England striker was able to open the scoring.
In the 38th minute, Armand Traore, on loan from Arsenal, took the ball to the by-line before cutting it back for Crouch to finish simply. Given what had just gone on at the other end, it was harsh on the Championship side.
At the interval, City's Lee Johnson, son of manager Gary, made his feelings about the penalty incident clear to referee Mike Jones – and was booked.
City started the second half with purpose and Jamie McCombe was unfortunate with a glancing header, from Lee Johnson's corner, that sailed just wide. Soon afterwards, with City in control, Maynard was thwarted again by James.
City refused to give up and when they hit Portsmouth with a counter-attack midway through the second half, Jamie McCombe should have done better with his finish, while Lee Johnson sent another chance just off target before the end.
Nadir Belhadj fed Kranjcar, on the break, for the second goal two minutes from the end, and Maynard was denied a consolation goal, when his 90th minute