For Serena Williams, 18 is not enough.

The world's No. 1 female tennis player told Chris Evert on ESPNW.com that her ultimate goal is to surpass Steffi Graf's record of 22 Grand Slam championships. The 33-year-old Williams is sitting on 18 after winning the 2014 U.S. Open in September for her lone win in a major.

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"Well, it's no secret. I'm going for the gusto. I'm going to try to catch up with Steffi," Williams told ESPNW. But right now I'm really focused on 19, which will begin in Australia. Whether I get there or not, I don't know. But I know if I get to 19, the second it happens I will be thinking of 20."

It's a bold yet predictable statement for Williams, who had an up-and-down 2014 - or rather a down-and-up year.

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She didn't advance past the fourth round in any of the first three Grand Slam events this year. Her third-round exit at Wimbledon was especially troublesome because she followed that effort with a bizarre pull-out of a doubles match with partner and sister Venus Williams, in which Serena appeared disoriented from the moment she stepped on the court and couldn't serve a ball over the net or even bounce a ball with her racket to her hand.

The scene was one of the biggest storylines of the 2014 women's tennis season, but Serena recovered and went on to win her sixth U.S. Open, as well as the season-ending WTA World Tour Finals in Singapore.

The Sidney Morning Herald reported that Williams and men's No. 1 Novak Djokovic were crowned 2014 World Champions by the International Tennis Federation on Thursday. She is the oldest women ever to be named ITF Singles World Champion.

"This was a year of challenges and triumphs, so to win another Grand Slam and retain my year-end number one ranking is an accomplishment I'm very proud of," she said.

Aside from her "rivalry" with No. 2 Maria Sharapova, whom Williams has beaten 15 straight times, the No. 1 player in the world will have to face challenges from up-and-comers Simona Halep (No. 3), Eugenie Bouchard (No. 5) and best friend Caroline Wozniacki (No. 8). Williams defeated Wozniacki in the finals of both the season-ending WTA event and the U.S. Open.

Williams listed a couple of improvements she wanted to make for 2015 in her conversation with Evert.

"Well, I want to move a lot faster on the court," Serena said. "I want to be more dynamic and just completely awesome out there. And I need to bring my serve back. My serve in 2014 was a little disappointing for me. I want my 2013 serve back, but a better version of that for 2015. I had so many double faults this year: I was hitting, like, seven in a match, and it was driving me insane."