The Paraguayan striker scored three times to lift BVB to a come-from-behind victory that saw them draw level with Bayern's single-season points record
Felipe Santana gave the hosts an early lead when he put the ball into his own net, but a double from Lucas Barrios followed by a third from Mario Gotze sent BVB clear ahead before half-time. Lautern pulled a goal back through Pierre De Wit shortly after the break, but Barrios responded by completing his hat-trick, and Ivan Perisic scored a late fifth.
Kaiserslautern started the game brightly, and Andrew Wooten was denied in a one-on-one situation before a pair of howlers from Santana resulted in the opener on 16 minutes. The centre-back was late in stepping in to cut off a pass to Konstantinos Fortuonis as the Greek attacker sprinted towards goal. Fortuonis cut to his right and appeared to push the ball too far wide, but Santana knocked it into his own net.
Two minutes later, Dortmund drew level as Barrios looped a backward header into the goal thanks to a fine cross from Patrick Owomoyela. On 26 minutes, the Paraguayan striker made it 2-1 as he stabbed home a low cross from Perisic.
Dortmund increased their lead in the 33rd minute through Gotze, who after receiving a clever flick from Robert Lewandowski took a touch and finished with aplomb.
Before the break, Lewandowski nearly had a goal of his own, but saw his shot rebound off the inside of the left post. Shortly thereafter came the half-time whistle, and the visitors entered the dressing room in full control.
De Wit gave the hosts a lifeline four minutes into the restart as he looped a free header over Mitch Langerak, but BVB stormed back to re-establish their two-goal cushion. After a howler from Tobias Sippel that saw the goalkeeper dispossessed inside his own penalty area, Barrios had his hat-trick. And on 76 minutes, Perisic struck the post but carried on in his attack moments later as he curled in a fifth.
The result lifts Dortmund, who are already confirmed champions, to 78 points, level with the record in the modern era. Based on the current points system, the 1971-72 Bayern Munich team would have the Bundesliga's best-ever tally of 79. However, Dortmund still have a chance to exceed that milestone next weekend in their final match of the season. Kaiserslautern, meanwhile, are already relegated and remain last in the Bundesliga standings.