Hertha Berlin have been dealt a huge blow with the news that the Germany Under-21 striker sustained the injury against Hoffenheim and will now miss his side's relegation play-off
The former Bayer Leverkusen youngster was forced to leave the pitch at the Olympiastadion on 61 minutes, in a match in which Otto Rehhagel's team managed to jump out of a certain relegation spot at the expense of Koln.
However, the extent of Lasogga's injury has now been revealed, as club doctor Uli Schleicher confirmed the attacker ruptured the anterior cruciate ligament in his right knee.
"He will be out for six months," Schleicher told reporters. "All the important steps are now under way [for his recovery]."
His absence will be keenly felt by Hertha, who had pinned their hopes on Lasogga leading the line in their forthcoming relegation play-off against the third-placed 2. Bundesliga finishers Fortuna Dusseldorf
The 20-year-old was the capital outfit's top scorer this season with eight league goals to his name, and played an instrumental role in their promotion back to the top flight last year.