Getting a good result in the first leg on Thursday is crucial for the northern German side, who have slipped to seventh in the Bundesliga after a disastrous second part of the season saw them record only four wins in 14 games.
They are also unlikely to claim a place in the Europa League next season.
Labbadia said his team had not played to their full potential in a shock 1-0 defeat to visitors Mainz at the weekend, but he could be the one paying the price if Hamburg fail to advance to the Europa League final on May 12 at their own stadium.
Labbadia will be able to call on striker Paolo Guerrero for the match against Fulham. The Peruvian is suspended from league duty for an attack on a fan.
"Unfortunately I had to watch from the stands on the weekend and could not help the team but I am available for the Europa League," said the 26-year-old striker, who missed most of the season with a cruciate ligament injury.
"I want to show that I am back in top form."
Hamburg will be missing experienced midfielder Marcell Jansen, whose World Cup hopes are in doubt due to a long-term injury.
UNCHARTED WATERS
Fulham have had to travel by train under the English Channel due to the flight disruptions from the volcanic ash spreading from Iceland, and the semi-finals of a major European competition represents uncharted waters for the west London club.
A little more than two years after coach Roy Hodgson arrived with the club in dire danger of relegation, any sense of inferiority on the European stage was blown away by their stunning victory over Juventus and their elimination of German champions VfL Wolfsburg in the last two rounds.
"The most important thing is staying focused on the task in hand and just get on with it," defender Aaron Hughes told www.fulhamfc.com.
"We know what's at stake and we've done really, really well to get here and we're eager not to let it go. We want to take that extra step to the final.
"There are a lot of us that haven't won something so prestigious. Obviously Danny Murphy's won a few trophies with Liverpool but the majority of us haven't so for us it would be a big thing."
Fans who endured their last two goalless Premier League games will be hoping for better things on Thursday but only a few hundred are expected to attend the game because of the travel difficulties.
Bobby Zamora, who has scored six goals in the competition this season, is Fulham's key weapon and is seeking his 20th goal in all to support his late bid for an England World Cup call-up.
Probable teams:
Hamburg: 1-Frank Rost, 6-Dennis Aogo, 5-Joris Mathijsen, 17-Jerome Boateng, 20-Guy Demel; 14-David Jarolim, 15-Piotr Trochowski, 8-Ze Roberto, 13-Robert Tesche; 22-Ruud van Nistelrooy, 9-Paolo Guerrero.
Fulham: 1-Mark Schwarzer, 2-Paul Konchesky, 5-Brede Hangeland, 6-Chris Baird, 18-Aaron Hughes, 20-Dickson Etuhu, 16-Damien Duff, 11-Danny Murphy, 11-Zoltan Gera, 29-Simon Davies, 25-Bobby Zamora.
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