The Robins came from behind to hold the Europa Conference League winners to a 1-1 draw in their initial encounter, and a home tie with either Nottingham Forest or Blackpool awaits the midweek victors.
Match preview
While Jarrod Bowen and the London Stadium faithful may have been pumping their fists when the Englishman drew first blood after just four minutes of the January 7 encounter, Bristol City boss Manning would end up raising his arms in elation thanks to the events of the second half.
With just over an hour played in the English capital, Tommy Conway's strike earned Bristol City a merited replay against their Premier League counterparts, who offered Manning his pathway into management with a spell as their Under-21s coach several years back.
Judging by his celebrations at the London Stadium, Manning would love nothing more than to send his former club packing, but Bristol City remain at risk of falling to their recent FA Cup curse; the Robins have alternated between fifth and third-round exits since 2017-18, losing at the former stage to Manchester City last year.
However, the hosting manager cut a much more dejected figure after Saturday's Championship battle with Preston North End, where a second-half double from Will Keane condemned Bristol City to a 2-0 Deepdale defeat, and Manning made no bones about his side's off-colour performance on the day.
That two-goal loss means it is now four games without victory for the Robins across all competitions - Conway's strike against West Ham also represents their only goal in those 360 minutes of football - but winning four of their last six contests as Ashton Gate does stand the hosts in good stead.
None of Arsenal, Manchester United or Brighton & Hove Albion had managed to break West Ham's defensive resistance in the weeks that preceded the visit of Bristol City, but with their rearguard finally breached again, David Moyes's men have an unwelcome addition to their festive fixture calendar.
Nevertheless, the 60-year-old affirmed straight after the stalemate that one more game on the calendar would be "fine" - even as the West Ham doctors deal with an influx of injury victims - and while Manning enjoyed his Hammers reunion last week, Moyes is now looking forward to a return to Ashton Gate following his two-year spell with Bristol City in the 1980s.
However, should the Scotsman's side fall short against their Championship counterparts, it would mark the first time since the 2016-17 campaign that they have been eliminated from the FA Cup this early on; the Irons have since suffered a trio of fourth-round exits between 2018 and 2020 and three successive fifth-round defeats.
While Bristol City's winless run stands at four matches, West Ham have now strung together an identical unbeaten streak and have gone five years without suffering an away FA Cup defeat to a lower-league team, going down 4-2 to AFC Wimbledon in 2019.
The Hammers also possess fond memories of their most recent trip to Ashton Gate in a knockout setting - they prevailed 1-0 in the fourth round of the 2014-15 tournament thanks to a Diafra Sakho effort - and that victory stretched their unbeaten run on Bristol City's turf to six games since a 3-2 loss in 1977.
Bristol City FA Cup form:
D
Bristol City form (all competitions):
W
W
D
L
D
L
West Ham United FA Cup form:
D
West Ham United form (all competitions):
W
L
W
W
D
D
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Team News
Bristol City have come through their last two clashes without any new fitness concerns to report, although Manning recently revealed that Kal Naismith has suffered a setback in his recovery from a hamstring injury.
A similar issue is plaguing Mark Sykes, who also stands to miss Tuesday's replay, while Haydon Roberts (ankle) and Ross McCrorie (infection) were back on the bench against Preston; the latter was even given a 15-minute run-out
Rob Atkinson and Ayman Benarous are also on the long road to recovery from anterior cruciate ligament injuries, and having lambasted his side's display at Deepdale, Manning should not be averse to making an alteration or two here.
In contrast, West Ham's winter injury woes worsened in the 1-1 draw, as Lucas Paqueta and Dinos Mavropanos both left the field in the first half, and there are fears that the former's calf injury could sideline him for a couple of months.
Mavropanos is not believed to have sustained anything other than a knock, but in another alarming sight, goalscorer Bowen appeared to be struggling with an ankle concern at the end of the match; the Englishman completed the full 90 but may now be spared for Tuesday's replay.
The Irons are already without Africa Cup of Nations duo Nayef Aguerd and Mohammed Kudus, as well as Michail Antonio (knee), while right-back Vladimir Coufal was also in the wars against Bristol City but should be OK for the replay.
Bristol City possible starting lineup:
O'Leary; Tanner, Vyner, Dickie, Pring; James, Williams; Bell, Knight, Mehmeti; Conway
West Ham United possible starting lineup:
Fabianski; Johnson, Ogbonna, Zouma, Emerson; Alvarez, Soucek; Benrahma, Ward-Prowse, Fornals; Ings
We say: Bristol City 0-1 West Ham United
While calls from Hammers supporters for their side to strengthen their attacking ranks fall on deaf ears, the travelling supporters ought not to expect a scintillating offensive display from their side if both Paqueta and Bowen miss out as feared.