Hamburg could not a find a way through the Furth defence in the first leg of their Bundesliga relegation play-off at the Imtech Arena.
The result leaves Mirko Slomka's men facing a nervous second-leg clash at the Trolli Arena on Sunday as Hamburg look to preserve their top-flight status.
The six-time German champions have competed in every Bundesliga season, however, midfielder Van der Vaart believes Hamburg will need to perform better if they are to maintain that record.
"They (Furth) started very well and we came into the game late, but we were better in the second half," Van der Vaart said.
"We still have a good chance of winning and we know we need to improve for Sunday.
"We're staying positive, though. A club as great as this belongs in the Bundesliga."
Van der Vaart and his colleagues will need to reverse their appalling away form if they are to succeed - only rock-bottom Eintracht Braunschweig picked up fewer points on the road than Hamburg's nine in the regular season.
