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."
|Silver supports NBA players speaking out on social issues|
|Mickelson ready for Masters after third straight top-six finish|
|Gattuso: My job is to be the players´ nightmare until season´s end|
|I wasn´t good enough – Guardiola reveals Wigan rejection|
|Dillon reigns supreme with overtime win at Daytona 500|
|Bubba Watson ends drought with third Genesis Open title|
|Brazilian derby between Vitoria and Bahia abandoned after red-card frenzy|
|Anderson ends barren spell with New York Open triumph|
|It was crazy, but I like that - Zidane revels in eight-goal Betis thriller|
|Asensio credits Zidane for Madrid´s thrilling Betis comeback|
|Zidane hopeful over Marcelo hamstring injury|
|Overton replaces injured Plunkett for Blacks Caps ODI series|
|Bonaventura claims Milan can catch Inter|
|Bravo for Claudio! Guardiola to pick keeper at Wembley|
|Mourinho hoping for reinforcements at Sevilla|
|´Quick-healer´ Groves hopeful over shoulder injury|
|Real Madrid become first side to score 6,000 goals in LaLiga|
|Real Betis 3 Real Madrid 5: Asensio at the double in LaLiga classic|
|AC Milan 1 Sampdoria 0: Bonaventura makes it 10 unbeaten for Rossoneri|
|Schurrle excited to finally link up with Reus and Gotze|
|Fit-again Hughes included in England squad|
|New number one Federer revels in ´unbelievable´ week|
|Real Madrid defender Marcelo suffers hamstring injury|
|Costa fumes referees ´want to give me a card´, but Simeone plays down penalty row|
|Thiem regains Argentina Open title|
|Stoger makes Dortmund history with Gladbach win|
|Championship Review: Leeds fight back for point, Norwich & Ipswich share derby spoils|
|Racing beat La Rochelle to go second, Castres edge out Bordeaux|
|Borussia Monchengladbach 0 Borussia Dortmund 1: Burki unbeatable as Reus returns to haunt Foals|
|FA Cup ´magic´ no surprise to Pochettino after Rochdale thriller|
|Rochdale hero Davies: This is every kid´s dream|
|Atletico Madrid will not stop in pursuit of Barcelona, promises Gameiro|
|Banks boot pays dividends for Treviso|
|Lucky 13 and second successive title for Kvitova after Muguruza classic|
|´Wrong image´ to blame for VAR confusion in Manchester United´s FA Cup win|
|Rochdale 2 Tottenham 2: Davies denies Kane in FA Cup classic|
|Rieder stretchered off as Wasps extend Chiefs´ slump|
|Atletico Madrid 2 Athletic Bilbao 0: Gameiro and Costa settle cagey clash|
|NHL commissioner Bettman condemns ´reprehensible´ Smith-Pelly abuse|
|Visser, Scott and Nel among six recalled by Scotland|
|Bhuvneshwar and Dhawan inspire India´s Wanderers win|
|Napoli set club record with another Serie A win|
|Froome disappoints in time trial as Wellens wins Ruta del Sol|
|Napoli 1 SPAL 0: Allan sends hosts top of Serie A again|
|Federer makes short work of disappointing Dimitrov|
|Allegri allays Higuain injury fears|
|Blackhawks fans ejected after racist heckling of Capitals´ Smith-Pelly|
|Allegri convinced Juve can get past Spurs|
|Sri Lanka sweep series after dominating Bangladesh|
|Everton fear ´long-term´ injury for Mangala|
|If it isn´t Madrid, it´s Paris - Hazard tires of speculation|
|Luiten claims Oman Open title|
|Torino 0 Juventus 1: Champions win derby but lose Higuain|
|Neymar exit made Barcelona stronger - Ter Stegen|
|Remove T20 cricket from international schedule - Bayliss|
|Injured Higuain forced off against Torino|
|Jesus confident of returning strong after knee injury|
|DeGale launches Twitter attack on beaten Eubank Jr|
|We had to change hotels – Ovrebo recalls fury after 2009 Chelsea-Barcelona semi-final|
|Spalletti: Inter board will decide my future|
|Munro blitz helps Black Caps progress despite defeat|
|Fabregas still wary of timeless Iniesta|
|Liverpool´s 30-goal hero Salah: There´s more to come|
|Valverde: Coutinho dropped for the good of Barcelona|
|Garcia floors Rios for ninth-round TKO|
|Ronaldo better than Neymar? No says Xavi|
|Donovan Mitchell caps NBA All-Star challenges with dunk success|
|Anderson outlasts Nishikori to reach New York Open final|
|Steve Nash, Ray Allen among Basketball Hall of Fame finalists|
|Kevin Love: It was necessary to clean house in Cleveland|