Eliminated on penalties by Serie A leaders Palmeiras, the hosts' Copa do Brasil campaign came to an end on Thursday, while Flu strode through to the quarter-finals.
Match preview
After picking up a point away to reigning Brasileiro champions Atletico Mineiro last week, Sao Paulo extended their unbeaten run to a sixth straight game. However, a familiar foe put an end to all that earlier this week.
Sao Paulo's last loss had come at the hands of Rio rivals Palmeiras before the two teams convened for the second leg of their Copa do Brasil tie, and they let a one-goal advantage from the first leg slip - the game ultimately going to a penalty shootout.
Therefore, losing the 'Choque Rei' derby 4-3 on spot-kicks will prove a bitter pill to swallow for Rogerio Ceni's men, who sit seventh in the Serie A table.
That position, though tenuous due to the tightly-packed nature of the current standings, represents a significant improvement from where Sao Paulo dwelt at this stage a year ago, when they were flitting around the bottom third throughout the first half of the 2021 campaign.
They also have a place in the Copa Sudamericana quarter-finals to look forward to next month, when they meet compatriots Ceara over two legs, having knocked out Chile's Universidad Catolica with an 8-3 aggregate win in the previous round.
Rogerio certainly has improved the fortunes of a side that seemed lost under former coach Hernan Crespo, and they have suffered only one home defeat in the league this season - a record sure to be put to the test by one of Brazil's form sides.
With a total of 13 points from the last possible 15, Fluminense have established themselves as early title contenders, as they occupy fifth place in the standings - just three points off the Serie A summit.
Four consecutive wins in the Brasileiro - the latest coming at the expense of Ceara last weekend - have been accompanied by an aggregate 5-1 crushing of Cruzeiro in the Copa do Brasil, following Wednesday's 3-0 win at Mineirao.
After giving veteran forward Fred a special send-off upon his retirement last Sunday, Flu should not miss his goalscoring input too much, as they have now racked up 14 goals across their last six matches in all competitions.
Head coach Fernando Diniz has his side well-organised at the other end, too, as they have conceded the third-fewest goals to this point of the Serie A campaign (15) and kept clean sheets in nearly half their league matches.
If Tricolor are to maintain such momentum, they must now negotiate back-to-back away fixtures, with Goias next up on the agenda, three days after their trip to Sao Paulo.
Sao Paulo Brasileiro form:
Sao Paulo form (all competitions):
Fluminense Brasileiro form:
Fluminense form (all competitions):
Team News
Sunday's game brings about a clash between the Brasileiro's leading scorers, as Fluminense's German Cano (10 goals) goes head-to-head with Jonathan Calleri of Sao Paulo, who has nine.
The former will start up front for the visitors, most likely in a lone role, backed by a three-man supporting cast featuring Matheus Martins. The talented teenager is already coveted by clubs in Europe, and has been promoted by Fernando Diniz to fill the boots of Luiz Henrique, who recently left for Real Betis.
Forwards Alan and Marrony have been brought in to replace the newly-retired Fred, but neither will be eligible to play until the transfer window opens next Monday. Nonetheless, Diniz has an almost injury-free squad from which to choose.
Sao Paulo, meanwhile, have signed striker Marcos Guilherme, having lost both Marquinhos and Gabriel Sara to English clubs over the past month, but the former must wait until next week for a possible debut.
By contrast with their opponents, Rogerio Ceni's squad has been decimated by injuries, with Alisson (knee), Robert Arboleda (ankle), plus Andres Colorado and Luan (both thigh) among those currently sidelined.
As ever, Calleri is set to be joined by Patrick up front for the home side, though former Italy international Eder provides an alternative option.
Sao Paulo possible starting lineup:
Jandrei; Costa, Miranda, Leo; Neves; Igor, Welington, Reinaldo, Gomes; Patrick, Calleri
Fluminense possible starting lineup:
Fabio; Xavier, Manoel, Nino, Paulista; Nonato, Andre; Martins, Ganso, Arias; Cano
We say: Sao Paulo 1-2 Fluminense
With both of the league's top marksmen on show, goals are almost guaranteed in this clash between two of Brazil's grandest clubs.
In fact, an entertaining affair could ensue if in-form Flu strike early - forcing their hosts to chase the game and leave gaps in behind - and the visitors are best equipped to edge it.