BY MICHAEL PAVITT.

Serbia’s Novak Djokovic and the United States’ Serena Williams will head into the Australian Open as favourites to win the opening Grand Slam event of the tennis season.

Neither will head into the tournament as the defending champion, despite having won the first Grand Slam of the year on six and seven occasions respectively.

World number one Djokovic suffered a shock defeat at last year’s tournament as he continued his recovery from a long standing elbow injury.

The Serbian triumphed at Wimbledon last year, while his upturn in form continued with victory at the US Open.

The top seed will begin his campaign with a match against American qualifier Mitchell Krueger.

Roger Federer will also hope to add to his six Australian Open titles, with the Swiss star having triumphed for the past two years in Melbourne.

The 37-year-old begins as the third seed, with Uzbekistan’s Denis Istomin set to provide his first round challenge.

Spain’s Rafael Nadal is seeded second, while ATP World Tour Finals winner Alexander Zverev is the fourth favourite as the German seeks his first Grand Slam title.

While the quartet will hope to take the headlines at the end of the tournament, the build-up has been dominated by Andy Murray’s retirement announcement due to an ongoing hip problem.

The Briton, a three-time Grand Slam winner, has targeted Wimbledon as the “end point” of his career.

He has admitted that hip pain could mean the Australian Open, where he has been a five-time runner-up, could prove his final event, however.

Murray has been handed a tough first round assignment, with Spain’s Roberto Bautista Agut heading into their match as favourite to advance.

The women’s draw is headlined by Williams, who will be seeking a first Grand Slam title since the 2017 Australian Open.

The American missed the next four Grand Slam events due to pregnancy and the birth of her first child.

She made her Grand Slam return at last year’s French Open and began to show her best form at the US Open, where Williams reached the final before losing to Japan’s Naomi Osaka in controversial fashion.

The American will be among the favourites to reach the final in Melbourne and she will begin her campaign against Germany’s Tatjana Maria.

Williams could be on collision course to face tournament top seed Simona Halep, with the Romanian currently seeking to build on her maiden Grand Slam triumph last year at the French Open.

The world number one and last year’s runner-up will face Estonia’s Kaia Kanepi in the first round.

Denmark’s Caroline Wozniacki is the defending champion and is seeded third heading into the tournament.

Germany’s Angelique Kerber, the 2016 winner, starts as the second seed.