Duck can be tricky and again careful consideration needs to be given to its sauce.
Roasted - Try to go with traditional reds from Bordeax or Burgundy, any full bodied Spainish red such as Rioja and reds from northern Italy, for example Barolo.
In Sauce - It depends on the type of sauce. Be adventerous, perhaps trying a white such as Semillon or a German Riesling if the sauce is based around apples or oranges. Cherry sauce requires a fruitier style such as New World Cabernets or Pinot Noirs.