Headliner Lleyton Hewitt on Tuesday withdrew from his defence of the Kooyong Classic title, opting instead for a practice match against world number four Andy Murray on Friday.
Australia's Hewitt, back inside the world top 50 after upsetting Roger Federer 6-1, 4-6, 6-3, in the final of the Brisbane International at the weekend, cited fatigue for the decision.
"It's obvious that this week is all about Australian Open preparation and about getting in as a good nick as possible," said Hewitt, ranked 43. "For the last four days in Brisbane, I played some tough matches in extreme heat.
"I have to do what's right for my body before the biggest event in my country, I've always been looked after well here and I take pride in having won this event twice.
But not wanting to let down organisers and his fans at the Australian Open warm-up event, the 32-year-old former number one said he would happily play a one-off match against Murray. "I want help support Australian tennis. I'm thrilled to get a practice match against another top player."
Murray arrived in Melbourne after winning just one round last week in Doha as the Scot played his first ATP tournament since back surgery in September.
Australia's 19-year-old Jordan Thompson, ranked 320, replaced Hewitt in the eight-man field.
World number seven Tomas Berdych of the Czech Republic, Switzerland's Stanislas Wawrinka, who won in Chennai at the weekend, Frenchmen Gilles Simon and Richard Gasquet, Spain's Fernando Verdasco, Kei Nishikori of Japan and Bulgaria's Grigor Dmitrov complete the line-up
World number eight Wawrinka said that after a 14-hour flight to Melbourne, he was hoping to be ready for Wednesday. "I started really well for sure this year, winning a title in my first event," he said.
"It was a great week for me. I'm certainly happy with the start of this season."
Fans will be treated to Australian Open champion and world number two Novak Djokovic playing a practice match on Thursday against Juan Monaco of Argentina as well as the Hewitt-Murray clash on Friday.