Gladbach's exit was the biggest shock on Tuesday with substitute Seydel scoring four minutes after coming on.
Phillip Tietz had put the hosts in front in the 23rd minute before Gladbach's Luca Netz equalised five minutes after the restart from an Alassane Plea.
Most other Bundesliga clubs fared better with holders RB Leipzig cruising past Hamburg SV 4-0.
Fellow Bundesliga club Eintracht Frankfurt also advanced, with a 2-0 win over Stuttgarter Kickers, as did Vfl Bochum and VfL Wolfsburg.
In an all-Bundesliga battle Hoffenheim demolished Schalke 5-1 to pile more pressure on the embattled Ruhr valley club.
Hoffenheim, who sit fourth in the Bundesliga six points behind leaders Union Berlin, enjoyed a stellar display against relegation-threatened Schalke, who have so far managed one Bundesliga win and only six points from 10 games.
Dabbur put the hosts ahead after five minutes from close range while midfielder Angelino doubled their advantage with a low shot from outside the box in the 16th.
Hoffenheim made it 3-0 through another Dabbur strike just before halftime as he fired the ball from a very tight angle into the far top corner.
Ozan Kabak and Pavel Kaderabek were also on target for the hosts while Schalke midfielder Dominick Drexler grabbed a consolation goal in the 69th minute.
Bayern Munich travel to Augsburg on Wednesday while Borussia Dortmund face Hanover 96.
