Brisbane, Australia - Novak Djokovic's upcoming defence of his Australian Open title was plunged into disarray on Tuesday as the Serb crashed out 6-4, 6-4 in his opening match at the Brisbane International.
The world number two was upset in his first match of the season and now has no chance to gain ranking ground this week on Roger Federer, who competes in Doha.
Gulbis earned his first win over his former teenage companion at a Munich tennis academy after losing to Djokovic at the French Open and Cincinnati Masters last year.
Djokovic lasted just 88 minutes as he was upset by the world number 53, with Gulbis breaking in the fifth game of the opening set to start his roll to victory.