On what could have been an even greater night for the African side, another shock result this time did not have the desired outcome as Switzerland's win over Serbia made Cameroon's progress impossible, irrespective of the 1-0 victory at the Lusail Stadium.
For a brief period Aboubakar's superb header in the third minute of added time had Cameroon believing in the impossible and federation president Samuel Eto'o frantically checking his phone in the VIP section for news from Stadium 974.
Aboubakar was shown a second yellow card for removing his shirt and when when the whistle sounded on Cameroon's first World Cup win in 20 years they did not have long to wait to discover their fate. Their joy was dampened after learning Serbia had not forced an equaliser.
Already-qualified Brazil had the luxury of making nine changes, including bringing in the 39-year-old Dani Alves to become his country's oldest World Cup player, but their under-strength team never fulfilled expectations.
One of those new faces Gabriel Martinelli provided the bright spark of a first half relatively low on chances with his powerful, twisting header from Fred's cross turned over early on by Devis Epassy.
The Arsenal forward's horizontal run along the edge of the penalty area in added time also forced Cameroon's second-choice goalkeeper into another fingertip save.
In between those two opportunities Cameroon's threat to Ederson's goal at the other end was limited, with Nouhou Tolo's dangerous cross repelled by the Manchester City goalkeeper, who then parried away Bryan Mbeumo's downward header.
The Brentford winger had the honour of registering the first shot on target of the tournament against the favourites.
Early in the second half Mbeumo teed up Aboubakar for an angled shot which had Ederson scrambling across his goal, but with news filtering through of Switzerland's lead over Serbia, Cameroon knew even if they were to take the lead it would not be enough to save them.
Manchester United left-back Alex Telles departed with an injury , covering his face with his shirt as he walked around the perimeter of the pitch, before Martinelli saw Epassy deny him for a third time after he cut in from the left onto his right foot.
The Cameroon goalkeeper was almost embarrassed by Eder Militao's bundled shot from the resulting corner but managed to recover and turn his fumble around his right-hand post.
Substitute Bruno Guimaraes failed to properly connect with Raphinha's cross as Brazil's second string continued to squander chances and were eventually made to pay.
Jerome Ngom Mbekeli swung over an inviting cross from the right and Aboubakar took full advantage to plant a header past Ederson.