A 36th-minute goal from Ritsu Doan took Freiburg to a 1-0 win at Darmstadt on Sunday, pushing the last-placed hosts closer to relegation on the same day Bayer Leverkusen hope to claim the title.
The lightning-fast Doan jinked in from the right, linking with striker Michael Gregoritsch who returned the ball for the Japan winger to curl the ball home.
Winless since October and with only two victories all year, the loss leaves Darmstadt dead last, eight points from second-last and 13 points from safety with five games remaining.
Freiburg's win lifts them to eighth, drawing them level on points with seventh-placed Augsburg and just outside the European spots.
Later on Sunday, Leverkusen -- who are still unbeaten after 42 games in all competitions this season -- can clinch the Bundesliga title for the first time with a win at home over Werder Bremen.
Leverkusen sit 13 points clear of Bayern Munich and Stuttgart and will move out of touch with a win on Sunday.
Alonso, who is in his first full season coaching after taking over Leverkusen midway through last campaign, pledged to stay with the club in March despite reported interest from Liverpool and Bayern.