Kei Nishikori is another high-profile absentee from the Australian Open.
Other form players include France's Gael Monfils, who won the lead-up Qatar Open in a depleted field, and his countryman Gilles Simon who rolled back the years to claim the ATP Maharashtra Open title. Referring to the final set of the thriller, which he won 6-3, he said: "It was an awesome final, an unbelievable moment for me in my life and it's great to be back here", as quoted by the Express.
Her sister Venus, who lost the all-Williams Australian Open final a year ago, has a tough opener against Belinda Bencic - who combined with Federer to win the Hopman Cup for Switzerland last week - and is also in the same quarter as U.S. Open victor Sloane Stephens.
"With Roger, I always felt that he was so gifted and able to do so many things so comfortably that as long as he stayed healthy and driven and enjoyed what he was doing, there was no reason he couldn't claw his way back", adds Annacone.
For a man who has enjoyed such domination in the sport, holding the top spot in the rankings for over four years, it will feel a tad unusual entering this particular Grand Slam some way down the list of favourites. She said it didn't leave her enough time to feel confident of winning a major.