The minnows took Liverpool's fellow four-time European champions Ajax to the brink of a shock defeat before finally bowing out on penalties in last season's qualifying round, and German star Hamann knows Benitez's boys must be ready for a difficult task when they travel to the Arnold Schwarzenegger stadium on Tuesday.
Hamann said: "This won't be an easy game at all. Graz only lost to Ajax on penalties in the Champions League qualifier last season, so we have been warned.
"The Austrian season also started three weeks ago, so while we still haven't played a competitive match yet, they've had plenty of football.
"I hope it will be to our advantage in the Premiership to have such a competitive start before we go to Spurs."
