Hamburg sack Labbadia
Hamburg, who visit the London club for the second leg of their Europa tie on Thursday following a 0-0 draw in the first leg, said there was no choice.
He will be replaced by Dutch assistant coach Ricardo Moniz until the end of the season, the club said.
"We analysed the situation and we saw that as things were we would not be able to succeed against Fulham," club president Bernd Hoffmann told reporters after meeting Labbadia earlier in the day.
"It was the last moment for us to react to keep our Europa League target in sight," he said.
Hamburg were crushed 5-1 by Hoffenheim on Sunday, dropping to seventh in the Bundesliga after a poor second half of the season in which they have won only four of their 15 league games since the winter break.
Labbadia, who took over last summer, had suffered a similar second-round collapse last season with Bayer Leverkusen.