Roger Federer said one of the biggest factors he had to overcome in his Australian Open first-round win over Jurgen Melzer was nerves.

The record 17-time grand slam winner was playing his first major tournament since last year's Wimbledon, having missed the second half of 2016 with a knee injury.

Federer was edgy in the first set and threw away a 3-1 lead in the second, but eventually sealed a comfortable 7-5 3-6 6-2 6-2 win.

The 35-year-old, who holds the unfamiliar seeding of 17th at Melbourne Park, conceded it took him time to settle on Rod Laver Arena - a venue where he has been crowned champion on four occasions.

"I think there were definitely some nerves there. I was feeling nervous once the match actually started," he said. 

"I was actually fine all day, warming up, in the warm-up five minutes with Jurgen. I felt fine.

"Then I hit four frames in a row. It was like, 'whew, it's not as easy as I thought it was going to be'.

"I think I struggled for a while to find that groove, that rhythm and everything. 

"Then you remind yourself how many times it has not been easy in the first round. Almost every time, except you get off to a flyer and you keep rolling. But that's not the whole time.

"So you have got to work. I'm happy I was made to work. Actually at the end I'm quite happy how I ended, which is most important."

Federer's absence on tour last year was the first time in his remarkable career he had missed such a prolonged period on the ATP Tour.

And the Swiss maestro reflected on an emotional return to the grand slam scene.

"It was a special moment walking out on the court. A special moment, you know, after match point," he added. 

"Match point; when you get to match point; when you win the match point - I think those three components make it special when you're coming back. 

"Obviously last year it also felt special in a way in Monaco when I came back after my first surgery ever.

"So I definitely see things a bit different when you've been gone for a long time or when you've come back from injury like I have in the last year or so."