Colombian James Rodriguez set up the burly Brazilian who pounced on the ball down the right in the 55th minute, outpaced a defender and slotted home a diagonal shot, silencing the home fans in the 30,000 strong "Quarry" stadium.
Braga, who were just two points behind Porto going into the match, wasted several good chances with Hugo Viana and striker Lima the main culprits.
The win puts pressure on second-placed Benfica who face a tough trip to Lisbon neighbours Sporting on Monday. The Eagles have 59 points behind Porto on 63 with Braga now five points off the pace.
"This championship will be discussed until the end but this was an important step for us," said Porto coach Vitor Pereira.