Hamburg coach Markus Gisdol said U.S. international Bobby Wood's goal had been the crucial moment in his side's 2-1 win over Schalke.
Wood struck to make it 2-0 as Gisdol's team won only their second home game of the season and inflicted an eighth defeat on Schalke.
The forward came off the bench in the 59th minute to double the lead provided by Nicolai Muller after former Arsenal defender Johan Djourou had failed to convert from the penalty spot.
Wood stormed into the box and beat two defenders before curling home his strike and Gisdol told Sky: "I was convinced that Johan would score -- but Bobby then scored instead.
"It was important we showed a reaction after the penalty and played for that second goal. The team's going along at 100 percent."
Hamburg's win saw them cut the deficit to the teams outside the relegation zone to just two points.
They have picked up 11 points from their last six matches and suffered only one defeat.
"We are united and on a good path," Gisdol said. "The team gives a lot. That's why we are delivering results."
Schalke captain Benedikt Howedes, whose side are now just five points ahead of Hamburg, told Sky: "We just played weak football. We never played more bad passes than we did in the first half."