Portuguese striker Hugo Almeida struck twice with Marko Marin and Mesut Ozil making it 4-0. Defender Naldo converted a 73rd-minute penalty before Markus Rosenberg completed the rout eight minutes from time.
"We played an outstanding match," Bremen coach Thomas Schaaf told reporters. "I have to congratulate my team because after the break (for international friendlies) my players quickly found their footing in this match. They just kept getting stronger."
Schalke 04 moved into third place on 25 points with a hard-fought 2-0 win against Hanover 96, who were playing their first match since the death of their keeper Robert Enke.
Jefferson Farfan headed in the first and substitute Jan Moravek, who came on for the Peruvian striker, added a second with his first touch in stoppage time.
MINUTE'S SILENCE
Hoffenheim are two points behind in fourth after defeating Cologne 4-0 while VfB Stuttgart salvaged a 1-1 draw against bottom Hertha Berlin, piling more pressure on coach Markus Babbel as they lie in 16th place.
Champions VfL Wolfsburg twice came from a goal down to level against visitors Nuremberg, who snatched the three points with the last kick of the match when Peer Kluge struck on the break.
All the matches started with a minute's silence in memory of Enke, who committed suicide last week.
Bremen, without injured captain Torsten Frings, top striker Claudio Pizarro and Tim Borowski, took the lead against Freiburg through Almeida who headed in a cross from Ozil in the 33rd minute.
Freiburg keeper Simon Pouplin's spectacular saves allowed them to go into the break with a one-goal deficit but Bremen shot out of the blocks in the second half, doubling their lead with a well-struck Marin free kick in the 55th.
Almeida made it 3-0 two minutes later and Ozil beat Pouplin from close range before Naldo scored from the spot in the 73rd and Rosenberg netted.
