Union earn hard-fought draw thanks to keeper Ronnow

But Union were always in the game and improved in the second half, captain Christopher Trimmel going close from distance and Yorbe Vertessen also being denied by Noah Atubolu after a good move. Aljoscha Kemlein also had a good chance for the Irons. 

Freiburg then could have won it late through substitute Lucas Höler and Philipp Lienhart in a flowing game, with a draw arguably the fairest result.  

Union sit seventh with just nine goals scored and eight conceded from 10 league games. 

It is the second stalemate in a row for Freiburg and also the second 0-0 of the season for the Berliners. 

Leaders Bayern Munich travel to promoted St Pauli, who have yet to win at home, in Saturday's main program of matches.   

Second-placed RB Leipzig host mid-table Borussia Mönchengladbach in Saturday's late game.