Prior to their trip to Brittany, Luis Enrique's double Champions League-winning side had managed just two points from their opening three matches in an uncharacteristically sluggish start to the league season.
Torres fires PSG to first win of Ligue 1 season
Torres fires PSG to first win of Ligue 1 season
They began their quest to win a third consecutive Champions League title by thrashing Slovan Bratislava 6-1 on Wednesday and four days later they are now off the mark domestically thanks to new signing Torres.
The close-season arrival from Barcelona, who scored the winning goal for Spain in the World Cup final this summer, netted a hat-trick midweek and followed it up with a sumptuous early strike at Brest's Stade Francis-Le Ble.
Torres now has six goals in five outings in all competitions for PSG.
"What matters to me is always helping the team, regardless of how much playing time the coach decides to give me, and doing my part. Whether that's through goals, assists, or my work on the pitch," the 26-year-old said.
The result sent the Parisians up to eighth in the league table, with an identical record to their hosts, who had been unbeaten heading into the encounter.
Ahead of kick-off, Brest paid tribute to their former coach Eric Roy, who died in June aged 58 after suffering from pancreatic cancer.
PSG got the crucial breakthrough in the fifth minute when Ballon d'Or winner Ousmane Dembele flicked a backheel into the path of the onrushing Torres.
