MELBOURNE, Australia -- Roger Federer and Novak Djokovic are each aiming for a record seventh men's Australian Open title and the draw has ensured they can't play each other at Melbourne Park until the final.

Serena Williams already has seven Aussie titles, and is a strong contender to add another after skipping her title defense in 2018 while she was on leave after having a baby.

Now seeded 16th, Williams was drawn into the same section Thursday as No. 1-ranked Simona Halep, the runner-up here last year. The pair could meet in the fourth round.

No. 1-ranked Djokovic starts at the top of the draw and will open against a qualifier. He has the potential of a second-round meeting against wildcard entry Jo-Wilfried Tsonga. He defeated Tsonga in the 2008 Australian final. Djokovic also has a potential quarterfinal against No. 8-seeded Kei Nishikori.

No. 4 Alexander Zverev is in the same half and looms in the semifinals if both players advance that far.

Defending champion Federer is in the bottom half of the draw with No. 2-ranked Rafael Nadal.

Aiming for a third consecutive Australian championship, a 21st Grand Slam crown and a 100th career singles title, Federer will open against Denis Istomin. And with No. 6 Marin Cilic in the same quarter, there's potential for a rematch of the 2018 final a few rounds early.

That's not in Federer's focus right now.

"The moment you find out the draw, that's when you shift your focus to the first round and only the first round -- not going for your seventh (title) or anything like that," said Federer, who was heading to the practice courts immediately after attending the tournament draw. "You try to really simplify it rather than look too far ahead. To win has to be the goal, but I try not to put too much pressure on it."

Cilic has Andy Murray, who is coming back from a long-term hip injury, in his section. Murray opens against No. 22-seeded Roberto Bautista Agut.

Murray won just two games in an incomplete practice match with Djokovic at Melbourne Park, showing signs he's still not fully fit after spending most of the last 18 months off the tour. Murray played at the season-opening Brisbane International last week, where he won his first-round match against James Duckworth but lost in straight sets to Daniil Medvedev in the second, limping between points and admitting he's still dealing with his troublesome right hip.

One of the most intriguing men's first-round matches features 2016 Wimbledon finalist Milos Raonic against mercurial Australian Nick Kyrgios, who is unseeded after his ranking slid from 13 into the 50s, but has tour-level wins over Federer, Nadal and Djokovic to his credit.

Serena Williams will face Tatjana Maria in the first round, and could meet either Genie Bouchard or Peng Shaui in the second round. Halep has a tough opening encounter against Kaia Kanepi and a possible third rounder against Venus Williams.

Third-seeded Caroline Wozniacki, who won her first Grand Slam title here last year after a tough final against Halep, is in the same section as Maria Sharapova and has Petra Kvitova at the top of her quarter.

Second-seeded Angelique Keber is in the same half as Wozniacki and has 2017 U.S. Open champion Sloane Stephens in her quarter.