The Germany internationals were withdrawn in the second half of the clash at the Weserstadion, which marked Dortmund's second straight Bundesliga win after a run of four top-flight games without victory.
And the club confirmed on their official Twitter account on Sunday that they expect to be without Reus for around a fortnight and Bender for a week.
"Marco Reus retired in the game in Bremen (due to) a torn muscle in his right thigh and is expected to be (out for) two weeks," Dortmund stated.
"Sven Bender has (injured) a muscle in his right thigh in the game and is expected to (be out for) one week."
Both players will therefore miss Dortmund's DFB-Pokal clash with Eintracht Frankfurt on Tuesday, with Bender potentially being fit for their league fixture at home to the same opponents next weekend.
