Freiburg secured an immediate return to the Bundesliga, one season after relegation to the second division, with a 2-1 win at Paderborn on Friday.
Goals from Mike Frantz and Nils Petersen, both set up by Maximilian Philipp in a three-minute spell just after the break, ensured Freiburg will finish at least second, earning automatic promotion.
With two rounds remaining, Freiburg has 69 points, five more than Leipzig, and 10 more than third-placed Nuremberg, which has a game in hand.
Even if Nuremberg, which is all but certain of at least a promotion/relegation playoff following St. Pauli's 2-0 defeat at 1860 Munich, wins its remaining three games, it cannot catch Freiburg.
It is Freiburg's fifth promotion to the top flight.