Djokovic thanks Ivanisevic tips after flurry of aces

Defending champion Novak Djokovic said he had been taking tips from serving maestro Goran Ivanisevic after he hammered down a series of aces in his first-up win at the Australian Open.

Djokovic smacked 14 aces and had a first-serve percentage of 65 per cent in his grinding 7-6 (7/5) 6-2 2-6 6-1 win over Germany's Jan-Lennard Struff in round one.

The Serb credited his work with Croatia's Ivanisevic, who served up more than 10,000 aces in his career and joined the 16-time Grand Slam winner's team last year.

"Throughout my career my serve was maybe a little bit underestimated because of the quality of the returns and the baseline play," he told reporters late on Monday.

"There were times I was struggling with an elbow injury and I had to change the technique of my serve and a lot of things were happening, but in the last year-and-a-half I feel great serving.

"Obviously I pray to have serving days like I had today all of the time. I know it's not possible but I can back up my serving game from the back of the court."