Hamburg held at home by Hanover
The visitors, who have won only twice in their last 18 league games, played the last half hour with 10 men after forward Jiri Stajner was sent off in the 59th minute after being booked twice in the space of seven minutes.
Hanover stayed 17th in the 18-team table with 24 points from 29 games, one point behind Freiburg who occupy the relegation play off spot after their 1-1 draw against VfL Bochum on Saturday and four points adrift of 15th-placed Bochum.
Bottom-of-the-table Hertha Berlin, who won 3-0 at Cologne on Saturday, are two points behind Hanover.
Champions VfL Wolfsburg, who are ninth, thrashed Hoffenheim 4-0 helped by two goals from Bosnia striker Edin Dzeko who joined Stefan Kiessling and Kevin Kuranyi as the league's joint topscorers with 18.
Andrea Barzagli and Zvjezdan Misimovic shared the other goals.