Borussia Dortmund were also boosted in their pursuit of a Champions League spot next season on Sunday by moving back to fourth position after coming from behind to win 3-1 at home to Eintracht Frankfurt.

On Saturday, second-placed Bayern Munich had won 5-2 at bottom side Darmstadt to trim the gap, but Xabi Alonso's unbeaten Leverkusen restored their 10-point lead with eight to play thanks to goals from Florian Wirtz, Adam Hlozek and Patrik Schick.

"We have an intense April ahead of us and hope all the boys return from their national teams without any problems," Alonso told reporters ahead of the international break.

Leverkusen have not lost in any competition all season but came the closest yet on Thursday when trailing 2-1 to Azerbaijan's Qarabag entering injury-time in their Europa League last-16 second leg.

But Schick popped up twice for another remarkable Werkself win and Leverkusen quickly carried on where they left off with Germany's Wirtz scoring in style after two minutes in Freiburg.

The hosts are hoping for another European adventure next season, having been battered by West Ham United in midweek, and Japan's Ritsu Doan equalised when he played a one-two with Lucas Holer and netted after 10 minutes.

The game was even until Freiburg goalkeeper Noah Atubolu failed to scoop up the ball and Hlozek had an easy finish on 40 minutes.

Fellow Czech forward Schick then expertly turned in Jeremie Frimpong's cross for 3-1 after the break before Yannik Keitel (79) set up a nervous finale.

The win stretched Leverkusen's record to 38 games unbeaten in all competitions this term and left Bayern with scant hope of a 12th straight title.

Dortmund were knocked down to fifth by RB Leipzig thumping Cologne 5-1 away on Friday but they are now a point above the Red Bulls.

Mario Gotze cleverly found the corner of the net on 13 minutes, but the 2014 Germany World Cup winner refused to celebrate against his former club.

Dortmund deservedly equalised through Karim Adeyemi on 33 minutes after constant pressure.

It looked like a winner would not come until Mats Hummels turned in Julian Brandt's free kick with a diving header on 81 minutes. Emre Can, earlier spared a red card by the video assistant, then netted a late penalty.

Australian Associated Press