The Rossoneri took the lead in Germany after 36 minutes through Filippo Inzaghi and looked like they would hold out for a victory.
However, Bremen pushed forward in the second half and eventually got on level terms with just six minutes remaining when Diego fired home.
"It's a good result," Ancelotti explained. "In the first half we saw a very good Milan while in the second half we suffered in the face of the opposition's physicality.
"They played the game on a physical level and made us suffer a lot," Ancelotti reiterated, no doubt referring to the five yellow cards referee Martin Atkinson had to dole out.
"The draw is a good reference point that we can use in our preparation for the second leg," Ancelotti concluded.
"They are a frightful team, although they have some gaps in their defence. We will have to be good to exploit them."