Ceni sensationally took his season tally in the Brazilian Serie A to six goals, while netting his 121st career goal in the process after converting an 18th-minute penalty on Wednesday.
However, Ceni endured a nervy outing from that point, gifting Flamengo an equaliser and missing a second-half penalty as 10-man Sao Paulo shared the spoils at the Estadio Cicero Pompeu de Toledo.
Sao Paulo - now third in the standings after their winless streak extended to three games - hit the front courtesy of Ceni, who netted a spot-kick following a foul on Alan Kardec.
Ceni was at fault in the 34th minute, fumbling a seemingly routine save into the path of Everton, who tucked away the rebound.
The veteran keeper had a chance to redeem himself three minutes into the second half after Sao Paulo were awarded a controversial penalty for a handball.
Replays appeared to show Samir handling the ball outside the area, though Ceni ultimately had his effort saved by opposing number Paulo Victor.
Sao Paulo were dealt a blow in the 74th minute, when Michel Bastos saw red, and Flamengo took full advantage, hitting the front through Alecsandro with three minutes remaining.
However, substitute Luis Fabiano came off the bench and equalised in the final minute as Sao Paulo earned a draw.
Sao Paulo dropped to third with 43 points from 24 games, a point adrift of second-placed Internacional, who accounted for Criciuma 3-0.
Flamengo have drawn their past three league fixtures to sit 10th in the table.
Defending champions Cruzeiro, meanwhile, extended their lead to eight points.
First-half goals from Marcelo Moreno and Everton Ribeiro saw Cruzeiro to a 2-1 win at Coritiba.
Bolivian star Moreno became the league's leading goalscorer with 12 goals after netting an eighth-minute penalty.
Brazil international Ribeiro doubled the lead six minutes before half-time, converting his own rebound inside the six-yard box.
Coritiba substitute Alejandro Martinuccio reduced the deficit in the 62nd minute but Cruzeiro held on as they moved clear at the summit.
Atletico Mineiro, who beat Cruzeiro on Sunday, prevailed 3-2 at home to Santos on Thursday.
Gremio kept their seventh consecutive clean sheet and extended their unbeaten streak to eight matches under Luiz Felipe Scolari after drawing 0-0 at Fluminense.
Scolari's men rose to fourth at the expense of Corinthians, who slumped to a 1-0 loss to Figueirense.
Palmeiras climbed off the foot of the table with a 2-0 win over Vitoria.
Elsewhere, Botafogo edged Goias 1-0 and Bahia beat Sport Recife by the same scoreline.
Meanwhile, Chapecoense eased past Atletico PR 3-0.
