Hamburg starlet Son Heung-min breaks foot
Hamburg said on their website that the South Korean 18-year-old suffered the injury as he scored the late winner in Wednesday's match.
"It is still not clear whether the South Korean will need to undergo an operation or how long he will be out of action for," added the club.
Son joined Hamburg two years ago and was promoted from the junior team to the professional side by coach Armin Veh for the pre-season matches.
The Bundesliga starts on August 20.