The northern Germany side slipped into the bottom three after losing 3-0 to Schalke last weekend while Hoffenheim are reeling after a 4-0 defeat to Nurnberg, which leaves them just two points above their guests this weekend.
Both sides are aware of the severity of the situation they find themselves in, according to Van Marwijk, who therefore expects it to be a scrap for the points.
"It's going to be hectic and exciting," he said on hsv.de. "It's important for both teams, and we've got to make sure we don't allow ourselves to get insecure.
"Just playing football is not enough to win games, you need more than that."
That added extra the Dutchman is talking about is a winning mentality, belief and self-confidence, all aspects his side have struggled to show for much of the season.
He is not going to give up looking for them, however, as he vows to turn things around.
"Situations like this give me even more energy," he said.
The same can be said for Hoffenheim coach Markus Gisdol, who has called on his side to "win, no matter how", further increasing the likelihood of a scrappy game at the Rhein-Neckar Arena.
"We don't need any magical football, we just need to do the basics," he added. "That means tackling well and breaking quickly."
Sejad Salihovic is back in contention for Hoffenheim while Michael Mancienne will be missing for Hamburg after breaking his finger. Johan Djourou is back, on the other hand.