Holden's future continues to be called into question by many, with the club on a run of five successive defeats in all competitions.
The Robins boss described the loss at Vicarage Road as a "terrible afternoon that will sit with us for a long time", with the team conceding a Taylor Moore own goal in the second minute and not being able to recover.
Since December 1, only Birmingham City and Wycombe Wanderers have picked up fewer points in the Championship than Bristol City, whose top six hopes are now hanging in the balance.
Shipping six goals on Saturday also means that only three sides in the division have conceded more across the whole campaign.
The Robins may take some confidence from the fact that despite their recent woes, their home form is still encouraging as they have won four of their last six matches at Ashton Gate.
It is certainly a vital period ahead for Holden if he keeps his job, with the club facing Middlesbrough (eighth) and Swansea City (third) before February finishes.
Reading claimed a 3-1 victory when Bristol City visited the Madejski Stadium in November - a result which brought to an end a five-game winless run.
Veljko Paunovic is in need of something similar on Tuesday as the Royals have hit a tricky run of form again, winning just once in their last five matches.
The Berkshire club were beaten 2-1 at home by Millwall on Saturday, taking the lead through Alfa Semedo's bizarre 50-yard goal in the first half before conceding twice in the final 15 minutes of the game.
The result has surely put Reading's automatic promotion hopes to bed as they are now nine points behind the top two, but the former Premier League side are currently secure of their playoff place as they sit in fifth, eight points ahead of Cardiff in seventh.
Only Brentford (55) and Bournemouth (43) have scored more goals than Reading (42) in the division, but Paunovic's side have also conceded the third most goals in the top half (34). The Royals have lost just one of their last eight away league matches, meanwhile, but five of those games have ended as draws.
Bristol City Championship form: LWLLLL
Bristol City form (all competitions): WLLLLL
Reading Championship form: WDWDLL
Holden admitted after Bristol City's defeat to Watford that Alfie Mawson is likely to miss the rest of the season due to an injury picked up against Sheffield United in the FA Cup.
Former Reading player Adrian Mariappa is likely to replace teenager Ryley Towler at left-back, with Holden expected to turn to experience in his time of crisis.
Joe Williams could return to the side after being rested against Watford due to fatigue.
Paunovic has confirmed that John Swift will be out for over six weeks with a hamstring problem, but George Puscas is set for a return within the next 10 days. Yakou Meite, meanwhile, is being assessed weekly.
Bristol City possible starting lineup:
Bentley; Hunt, Vyner, Kalas, Mariappa; Paterson, Lansbury, Williams; Wells, Diedhiou, Semenyo
Reading possible starting lineup:
Rafael; Holmes, Morrison, McIntyre, Richards; Semedo, Laurent; Olise, Rinomhota, Ejaria; Joao
We say: Bristol City 0-1 Reading
The result of this game will hinge on Bristol City's response to their drubbing at Watford; they could go into their shell and be beaten again or could set out to prove their doubters wrong and get back on track with a win. Reading will not be an easy side to overcome, though, and we think that the Royals will be the victors.