Tommy Haas plays against Novak Djokovic in a Men's Quarter Final match at the 2009 Wimbledon Tennis Championships. (Glyn Kirk/AFP/Getty Images)
The German 24th seed, a first-time quarter-finalist here, broke in game 11 of the opening set and served out to take the lead after 45 minutes.
Djokovic wasted three set points in the second set tiebreak before Haas wrapped it up 8-6 before the Serb mounted a comeback by taking the third.
But his recovery failed to convince and the German, a former world number two whose career has been blighted by injury, stormed to a 4-1 lead in the fourth and sealed it when Djokovic netted a forehand service return.
He will play Swiss second seed Roger Federer for a place in Sunday's final.