The Citizens have booked their place at the showpiece event courtesy of a 3-0 victory over Urawa Red Diamonds in the semi-finals on Tuesday, with an own goal from Marius Hoibraten followed by second-half strikes from Mateo Kovacic and Bernardo Silva.
Before the contest, Man City were boosted by the return of star playmaker De Bruyne to first-team training, while both Haaland and Doku were not involved despite travelling to Saudi Arabia.
De Bruyne has been sidelined since August with a hamstring injury but he has recently made progress in his recovery and was back on the grass with his teammates on Monday.
As for Haaland, the striker has missed City's last three matches with a "bone stress reaction" in his foot, while Doku has been absent from the last four games with a muscle problem.
All three players were left out of Pep Guardiola's 23-man squad for the semi-final clash against Urawa and watched on from the stands at the King Abdullah Sports City Stadium.
The Man City trio are now ineligible to play in Friday's Club World Cup final, as tournament regulations set by FIFA state that only the same 23 players selected for the last-four tie are available to feature in the showpiece event.
Citizens youngsters Max Alleyne, Mahamadou Susoho and Micah Hamilton are all said to have replaced Haaland, De Bruyne and Doku in the 23-man squad at the last minute, and they are in contention to feature in the final against Fluminense.
Although the absence of Haaland, De Bruyne and Doku will be considered as a major blow for Man City, Guardiola has confirmed that the former two are still not fit to feature anyway, while the latter is also thought to need more time to make a full recovery.
Discussing De Bruyne at a post-match press conference, Guardiola said: "Kevin started training yesterday and will train with us tomorrow but it's been three months so he cannot play in the final, but he is getting better."
Providing an update on Haaland, the Citizens boss briefly added: "Erling still cannot train."
All three players now face a race against time to be fit for Man City's next Premier League fixture against Everton at Goodison Park on December 27, before the Citizens conclude 2023 at home to Sheffield United three days later.
Guardiola believes his squad has benefitted from their trip to the Middle East, adding: "Here we spend more time together. We have an incredible captain with Kyle [Walker] - he has organised many things for the team.
"But in terms of training, no way - we sleep, rest and try to be ready on the day of the game. Of course we will prepare something the day before the game but we need to rest good.
"Being here is unbelievable for us. We don't take it for granted - we may never be back again. We will try but it is difficult! The semi-final is always so hard. The expectations in Barcelona and Bayern Munich is so high, so we knew it would be a difficult few days.
"Now we try to arrive good, and I am pretty sure the players will try to win the only title we miss and don't have. They will want to give the club this step for our future."
Man City will attempt to become world champions for the first time in their history and become just the fourth English team to win the Club World Cup when they face Fluminense, who beat Al Ahly 2-0 in their semi-final on Monday.