Hamburg's Joris Mathijsen grabbed the lead on nine minutes on a freezing day and Marcell Jansen made it 2-0 in the 36th four minutes after Jerome Boateng was sent off for a foul on Marko Marin. Naldo pulled one back for Bremen in stoppage time.
The win lifted Hamburg into fourth place on 31 points with Bayer Leverkusen ending the first half of the season as leaders on 35. Bremen are sixth on 28.
Schalke 04 stayed in second, a point off the pace while Bayern Munich crushed Hertha Berlin 5-2 on Saturday to remain in third on 33. The season resumes on January 15.
"This is a fantastic result for us," Hamburg coach Bruno Labbadia told reporters.
"This was the cherry on top of a first half to a season which had everything. Our best start ever and extremely bad luck with injuries," he said. "My team took it all and we are now in touch with the top spots. We can only be satisfied."
Hamburg, eliminated last year in the German Cup and UEFA Cup semi-finals by Bremen who also ended their championship hopes, took an early lead when Mathijsen headed in at the far post.
Bremen, who had only lost twice in the league until Sunday, quickly recovered and came close when Naldo rattled the crossbar with a volley in the 27th minute.
The hosts were left with 10 men five minutes later when Boateng was red-carded after bringing down Marin at the edge of the box.
But it was Hamburg who scored again when Eljero Elia sliced open the Bremen defence with a masterful through ball for Jansen who had no trouble beating keeper Tim Wiese.
Bremen squandered a good chance to cut the deficit before the break when Sebastian Proedl managed to head wide from two metres.
After the re-start they launched waves of attacks, twice more hitting the bar through Aaron Hunt and Marin.
