Former champion Stan Wawrinka only decided on Saturday he would play the Australian Open as he prepares for a return from knee surgery.
The Swiss star has been sidelined since Wimbledon last year, having undergone surgery in August.
There were doubts the 2014 champion would be ready for the year's first grand slam, particularly after he withdrew from the Tie Break Tens exhibition event on Wednesday.
But Wawrinka, 32, confirmed on Saturday he had decided he would play the Australian Open.
"For me, I think the fact that I'm here and I'm going to play the first one, it's a big victory," he said.
"It's the best that I could have dreamed when I had the surgery, is to be here sitting in front of you and to say, 'OK, I'm going to play the first match'. That's something really good from my side, especially from the knee.
"The knee is getting way better. I still have a lot of work to do physically and also tennis-wise to be at my top level. I'm going to take the time I need for that. I know I need to get through those.
"I need to start somewhere anyway. I think here was a good start. It's a good place to start, to get pushed, to see also mentally how I'm going to react, how I'm going to feel when I'm going to be playing matches."
Wawrinka, the ninth seed, will face Ricardas Berankis in the opening round at Melbourne Park.
The three-time grand slam champion said he would need to be cautious on his return.
"It's the most important for me to be careful with the knee. That's why I waited until the last minute to decide if I was going to play or not," Wawrinka said.
"We decided with my team that the practice of today will make the decision if I'm ready or not. For me, most important was to make sure the knee doesn't risk anything.
"There's always a little risk, for sure, especially starting after six months in a match, you're going to get more tight, you're going to get nervous, you're not going to feel as comfortable in a match as in practice.
"But the knee is staying there, so that's the most important."