Maria Sharapova has two grand slam titles in the bag and has attained world number one status, but the Russian still believes her best is yet to come.
The world number five, a favourite for the Jan. 14-27 Australian Open, won Wimbledon as a 17-year-old in 2004 and believes she is still getting better.
"I love the work that I put in on the court and I know that some day it will pay off," Sharapova, runner-up in Melbourne 12 months ago, told reporters on Saturday.
"Saying that, I'm still 20 years old. I've said it many times, I don't think this is the peak of my career. I believe that there are many more years to go, and I'm going to learn from all those experiences within those years."
Sharapova said world number one Justine Henin was the "big favourite" and that defending champion Serena Williams and her sister Venus were also big threats for the title.
But the Russian said her never-say-die attitude would stand her in good stead over the next fortnight.
"I've proven it before and I've done it before, so I don't think you can ever count me out," she said.
"No matter how confident or not, no matter where my ranking is, I'm one of the toughest competitors out there. I never leave the court without giving 100 percent, and that's why I think I gain a lot of respect from my fans and from the tennis audience. It's what I love to do."
Sharapova suffered a shoulder injury in 2007 which caused her to alter her service action, but said she felt fully fit after the off-season and was raring to go.
"I'm feeling really good," she said. "I had a really good off-season. Injury-free. I worked really hard. I put a lot of dedication into it. Waking up every single morning, I was looking forward to practice, getting better.
"It was really refreshing because after a pretty difficult year it was great to be able to play tennis for such a long period of time without feeling concerned or worried about getting injured."
The fifth seed could face former world number one Lindsay Davenport in the second round in what will be the American's first grand slam tournament in 16 months, after a year off in which she had her first child.
Sharapova said she would be in for a tough match if she faced the American, champion at Melbourne Park in 2000.
"The bottom line is that she's a dedicated champion," she said.
"She's really good at what she does. Without a doubt, she is going to be playing on a good level again. But we've got to take care of business in the first round first."