A first-half goal from Brazilian international Igor Jesus proved the difference as Botafogo all but sealed a place in the knockout rounds in front of a 53,699 crowd at the Pasadena Rose Bowl.

French champions PSG are widely regarded as one of the favourites for FIFA's 32-team tournament after a dazzling season which culminated with a scintillating 5-0 demolition of Inter Milan in the Champions League final last month.

But their hopes of securing a victory which would have seen them become the first side to reach the last 16 were stymied by a resilient performance from their opponents from Rio de Janeiro.

"A lot of people wondered, but we showed how strong Botafogo is," goalscorer Jesus said after the win. "It was a difficult game, and we had to defend well, and we did our job and scored a goal.

"We're really happy -- we knew how important this game was. One team was the champion of the Champions League, the other team was the champion of South America," added Jesus, who had been strongly linked with a move to English Premier League side Nottingham Forest earlier this year before opting to stay with the Brazilians to play in the Club World Cup.

"I think I made the right choice to stay in Botafogo," Jesus quipped.

- 'Intense' -

PSG coach Luis Enrique said his team had expected a tough battle.

"We knew it was going to be a very difficult match -- they defended very well," the Spaniard said.

"This Club World Cup is very intense and difficult, and all the teams are highly motivated, especially when they're playing against us."

The PSG manager though was adamant that the European champions still had plenty of time to resurrect their campaign.

"If there's a team that can turn it around, it's our team," he said. "We've got to analyse this and there's things we can improve. But I think our performance was good."

PSG picked up where they had left off in Sunday's 4-0 Group B rout of Atletico Madrid, with Khvicha Kvaratskhelia testing Botafogo goalkeeper John with an early curling effort after just two minutes.

But that early effort was as close as PSG came to scoring in a scrappy first half punctuated by a series of niggling fouls that prevented the European champions from settling into their passing game.

Botafogo's midfield trio of Marlon Freitas, Gregore and Allan worked tirelessly to close down Vitinha, denying the skilful PSG playmaker time and space to launch attacks despite dominating possession.

Instead it was Botafogo who took the lead with a goal against the run of play on 36 minutes.

Jefferson Savarino's perfectly weighted through ball split the PSG defence and sent Jesus racing through on goal.

The Botafogo striker did brilliantly to wrongfoot the covering Willian Pacho before sweeping a shot that took a slight deflection past PSG goalkeeper Gianluigi Donnarumma on its way into the net.

PSG continued to dominate possession through the second half, and spent long periods camped in the final third.

But Botafogo's defence held firm and the result leaves the Brazilians firmly on course for the last 16, with a final group game against Atletico Madrid to come in Pasadena on Monday.