Marmoush on target as Frankfurt beat Gladbach in DFB Pokal, Freiburg & Bremen win
Frankfurt were reduced to 10 men when Arthur Theate was sent off for a handball outside the box just 15 minutes in, his second straight red card.
French forward Hugo Ekitike put the five-time winners in front in first-half stoppage time but Gladbach's Ko Itakura levelled things up at the start of the second.
With 20 minutes remaining, Marmoush put the undermanned Eagles back in front, his 11th goal in 13 matches in all competitions this season.
A Matthias Ginter goal and a penalty to Vincenzo Grifo, both in the first half, took Freiburg to a 2-1 home win over three-time winners Hamburg, who scored through Jonas Meffert in the second half.
Elsewhere, Hertha Berlin beat Heidenheim 2-1 at home thanks to goals from Derry Scherhant and Michael Cuisance. Heidenheim pulled one back through Stefan Schimmer in the 89th minute.
Six-time winners Werder Bremen beat Paderborn 1-0 with Marvin Ducksch scoring the only goal.
On Tuesday, Borussia Dortmund were beaten 1-0 in extra-time away at Wolfsburg, while RB Leipzig and defending champions Bayer Leverkusen had comfortable wins.
Later on Wednesday, 20-time champions Bayern Munich travel to Mainz.