Freiburg held resilient most of the match, but in the end Borussia Dortmund's attack was too much as they won 3-1.
Borussia Dortmund joined leaders Bayern Munich atop the Bundesliga table with a 3-1 defeat of Freiburg on Friday.
Bayern Munich manager Carlo Ancelotti stressed the importance of rotating players ahead of their match against Hamburg.
Bremen signed Gnabry, 21, for a reported fee of £5 million last month, with the German's contract with Arsenal due to expire next summer.
Bayern Munich winger Arjen Robben will have to wait for his first start in over six months when the German champions travel to Hamburg on Saturday.