Forest Green sit bottom of League One with a distance between themselves and safety, whereas Birmingham have recently endured a run of three consecutive losses in the Championship.
Match preview
Forest Green have been on a remarkable journey over the past 20 years which has seen them rise from the shadows of regional football into the third division of the English pyramid after winning the League Two title last year.
However - like any smaller club which enjoys a successful period - Rovers had vultures circling around key components of their winning formula during the summer, with ex-manager Rob Edwards moving onto an attractive role with Watford and crucial first-team players such as Kane Wilson departing.
Those exits have made the step up to League One even more challenging than anticipated, with Ian Burchnall's men sitting bottom of the league standings, having collected just 20 points from 25 matches.
The Gloucestershire-based club are currently going through their most worrying run of form in this campaign, having lost four-straight games over the festive period, a record which will give them little optimism heading into a cup clash with second-tier opposition.
Despite the struggles Rovers are having at this moment, there could not be a better incentive to earn a shock win on Saturday - victory against Birmingham would secure the club's passage to the fourth round of the FA Cup for the first time in their history.
Birmingham boss John Eustace has been keen to keep everyone associated with the club grounded this season despite a positive start, reminding supporters and players that they must stick together through inevitable tough periods in the campaign.
The time for Bluenoses to put that advice into action is now - with Blues experiencing their first real wobble of the season, having lost three successive matches in a very limp and uninspiring manner.
Second-half goals from Matt Crooks and Chuba Akpom condemned Eustace's men to a 3-1 defeat against Michael Carrick's Middlesbrough last time out, with the hosts at St Andrew's looking fatigued despite a number of changes that were made to the starting XI.
Blues' small squad is being tested to the limit with the wave of recent injuries to first-team personnel, with many players operating out of their normal positions as Eustace stays faithful to a 5-3-2 formation.
For the reasons mentioned above, a pause on league action and the arrival of the FA Cup may have come at the perfect time for Birmingham - although their recent record in the competition is not too impressive, with Blues being eliminated at the third-round stage in five of the last seven seasons.
Forest Green Rovers FA Cup form:
W
W
Forest Green Rovers form (all competitions):
W
W
L
L
L
L
Birmingham City form (all competitions):
L
D
W
L
L
L
Team News
Forest Green suffered a massive blow this week with striker Connor Wickham departing after the expiration of his short-term contract, meaning the likes of Josh March and Jamille Matt will need to step up with the goals to keep the club in League One.
Defender Jordan Moore-Taylor remains sidelined for the hosts on Saturday, meaning new arrival Brandon Cooper could be handed his debut at The New Lawn in this FA Cup clash.
Birmingham have been hit with another injury within their ranks over the past week, with Marc Roberts being forced off in the first half against Middlesbrough with a hamstring strain.
The 32-year-old joins Dion Sanderson in the collection of unavailable defenders at the club, meaning George Friend, Auston Trusty and Maxime Colin will be asked to form a makeshift back three - that is if Eustace does not opt to bring in academy players to the matchday squad.
Scott Hogan has not featured since before the World Cup break due to a hamstring injury, with Eustace hopeful the forward will be able to return to action against Forest Green in order to bolster a Blues attack which has looked blunt in recent matches.
Forest Green Rovers possible starting lineup:
McGee; Godwin-Malife, Casey, Cargill; O'Keeffe, McGeouch, Hendry, McAllister; Peart-Harris, Stevenson, Matt
Birmingham City possible starting lineup:
Etheridge; Colin, Friend, Trusty; Graham, James, Bellingham, Bacuna, Longelo; Deeney, Hogan
We say: Forest Green Rovers 0-1 Birmingham City
Forest Green have been on a poor run of form and will not be confident of progressing into the fourth round with a win against Championship opposition on Saturday.