Uzbekistan's Denis Istomin embraces Serbia's Novak Djokovic after winning their Men's singles second round match in Melbourne, Australia on Jan 19, 2017. [Photo/VCG]

MELBOURNE — Six-time Australian Open champion Novak Djokovic has been upset in a shocking second-round loss to Uzbekistan wild card Denis Istomin.

Djokovic was aiming to be the first man to win the Australian title seven times, and had won all his previous six head-to-head meetings against Istomin.

It was destined to be a long Thursday afternoon on Rod Laver Arena for Djokovic, though, when he needed 24 serves and a quarter of an hour to hold in the first game, saving six break points.

After 4 hours and 48 minutes, he sent a service return long to give No. 117-ranked Istomin a 7-6 (8), 5-7, 2-6, 7-6 (5), 6-4 win.

"All the credit to Denis for playing amazing. He deserves to win," Djokovic said. "He was the better player in the clutch moments — he stepped it up and played aggressive.

"Obviously, I was not pleased with my performance overall, but I have to congratulate my opponent. Whenever he needed — he came up with a big serve, big play."Istomin, who dropped out of the top 100 last year, had never beaten a top 10 player at a Grand Slam tournament.

"It is the biggest win for me. It means so much," Istomin said. "Now I feel I can play with these guys, and to be with them on the same level."His only previous win in 33 matches against a top 10 player was in 2012 at Indian Wells, when he beat No. 5 David Ferrer.