MELBOURNE, Jan 17 (Reuters) - Novak Djokovic's bid for a fourth successive title at Melbourne Park shifted up a gear with an impressive 6-3 6-3 7-5 win over Uzbek Denis Istomin on Friday, booking the Serb a place in the Australian Open fourth round.
The second seed was a model of controlled aggression under the lights of Rod Laver Arena, punishing Istomin's lack of court speed before picking him off with 31 crisp winners.
With new coach Boris Becker watching from the player's box, Djokovic was ruffled when broken for the first time serving for the match at 5-4 and threw a few icy stares at a rowdy pocket of fans.
But he roared in triumph after breaking back immediately and closed it out on the second match point when Istomin pushed a shot wide. Djokovic will play Italian 15th seed Fabio Fognini for a place in the quarter-finals.
(Reporting by Ian Ransom; Editing by Ed Osmond)