RB Leipzig secured a spot in the Champions League after a 2-1 win against St Pauli on Saturday, while VfB Stuttgart prevailed 3-1 to beat Bayer Leverkusen in the direct duel for a spot in the Bundesliga top four.
While Stuttgart moved up to fourth, Leverkusen dropped to sixth after being leapfrogged by Hoffenheim, who defeated 10-man Werder Bremen 1-0.
The dispute for the fourth and final spot will go down to the last matchday next weekend.
Stuttgart and Hoffenheim are tied on 61 points, with Leverkusen three points behind them.
Elsewhere, Augsburg still have chances of qualifying for the Conference Leauge after a 3-1 win against Borussia Mönchengladbach.
Champions Bayern Munich visit relegation-threatened VfL Wolfsburg later, following their mid-week Champions League elimination after a defeat to Paris Saint-Germain in the semi-finals.
If Wolfsburg drop points, they won't be able to leave the bottom three anymore, meaning that their only change of staying in the Bundesliga is securing a spot in the relegation/play-off spot.
A setback for the Wolves, however, would mean safety for Bremen and Cologne.
Leipzig make Champions League return
Last season, Leipzig missed Champions League qualification for the first time since 2017-18. This time they join Bayern and second-placed Borussia Dortmund in top competition.
Xaver Schlager, who's leaving the club at the end of the season, scored in his final home game to give Leipzig the lead in the 45th minute.
Christoph Baumgarter's header after a corner hit Schlager, who took a shot before firing the ball into the net.
The hosts increased their lead in the 54th once again after a corner. This time, David Raum placed the ball onto the head of Willi Orban, who guided it past goalkeeper Nikola Vasilj.
Abdoulie Ceesay pulled one back for the hosts in the 86th but his late strike didn't kickstart a comeback for St Pauli, who now face a must-win clash against relegation rivals Wolfsburg next Saturday.
Stuttgart's future in their own hands
Stuttgart now have the Champions League qualification in their own hands after they recovered from Leverkusen's dream start with a goal in the first minute.
Christian Kofane teed up Aleix Garcia on the left and the Spaniard rushed into to the box to collect the ball and fire the opener past keeper Alexander Nübel.
But Stuttgart fired back quickly and were level just four minutes later through Ermedin Demirović's goal.
Following a lengthy video review, Stuttgart were awarded a penalty after a challenge from Edmond Tapsoba on Demirović and Maximilian Mittelstädt gave the hosts the lead shortly before the break.
Deniz Undav sealed the victory in the 58th, finishing off Jamie Leweling's cross with a first-time shot.
A win at Eintracht Frankfurt next weekend is enough to secure Stuttgart a Champions League spot without relying on other results.
Leverkusen's situation is more complicated. They need a win against SV Hamburg and both Stuttgart and Hoffenheim (who visit Gladbach) to lose their respective matches.
Hoffenheim's hopes are still alive thanks to Bazoumana Toure's winner against Bremen, who had Yukinari Sugawara sent off in the fifth minute.
