Serena Williams squints her eyes and thinks. So many things come natural to her. When asked if she recalls her first match at Arthur Ashe Stadium, she is unsure.

"I don't remember," Williams says. "I want to say maybe I played Spirlea, yeah? Pulled that out of my memory. That was a long time ago. I remember winning that and feeling really good. It was a really tough match for me, so I don't remember how I felt, I just remember winning that match."

Uh, actually she didn't. That's how long ago it was.

A 16-year-old Williams made her U.S. Open debut in 1998. After advancing to the third round, she got her first chance to play in Arthur Ashe Stadium. She lost to 24-year-old Irina Spirlea 6-3, 0-6, 7-5.

Serena Fist Pump

One year after losing to Spîrlea, she won her first of six U.S. Opens and 21 Grand Slam titles. Her career prize money of $73,293,424 is more than double of the next player.

Williams, who will turn 34 on Sept. 26, has a résumé that makes an argument for being the greatest tennis player of all-time and yada, yada, yada. But the real story is what Williams is doing at her age.

Serena Scream

Williams turned 30 just after the 2011 U.S. Open. As the No. 28 seed, she reached the final, but was trounced 6-2, 6-3 by Samantha Stosur. For the first time since 2006, Williams went a calendar year without a Grand Slam.

Williams had nothing to be ashamed of. A career of 13 grand slam titles would have been more than enough.

Instead, Williams has strung together arguably her four strongest years, including her best season in 2015. Eight of Williams' major titles came after her 30th birthday. She is 48-2 this season and in July, she became the first No. 1 player in WTA history to have double the points of the No. 2 player.

Imagine Derek Jeter batting .375 last season or Michael Jordan winning an MVP with the Wizards or Wayne Gretzky still notching 150 points in his Rangers twilight.

The last time a 30-something woman's player won two Grand Slams in a season was Martina Navratilova in 1987 at 30. Williams has three at 33 and there is still one to go.

"Getting stronger is difficult," says 14-time men's Grand Slam champion Rafael Nadal. "She is amazing. With all the things that she is doing, I'm just going to congratulate her for all the success and wish her the best. It will be amazing if all [the records] happen."

Serena Trophy

With a victory at this year's U.S. Open, Williams will tie Steffi Graf's record 22 Grand Slam titles (Margaret Court has 24 but 13 before the Open Era) and become the second female to win a calendar Grand Slam. Graf did it in 1988, bridging ages 18 and 19.

"I feel like there's always another record," Williams says. "Then there's always another person to catch up with or to pass. I never really thought I would be in this position where I would even be talking about records, talking about passing Steffi Graf or even mentioning Margaret Court."

Another record: Williams is tied with Chris Evert for most U.S. Open title at six.

"I had no idea of that," she says. "That sounds really cool. But hopefully if things don't work out this year, I'm obviously going to be here next year and have another chance."

Since 2012, Williams has worked with coach Patrick Mouratoglou, a move she credits for putting together the second act of her career. The founder of the Mouratoglou Tennis Academy in France, he became Williams' first coach aside from her parents, Richard Williams and Oracene Price.

Players do not really fire their parents, and Williams still considers her father a coach. Mouratoglou was a catalyst to a career Richard built.

"I think my father is probably the best coach ever because if we talk about numbers, he's got a lot and he's only had two players," Williams says. "Imagine if he had three."

Serena And Venus

Serena and Venus have combined 28 singles titles and 13 in doubles in Grand Slams, plus Olympic gold medals (two singles, three doubles).

Graf was the unquestioned queen of the Open Era until Williams' late career push. Graf's 377 weeks at No. 1 in the world still has a cushion, but her other records are vulnerable.

"I've seen a lot of things that she's posted," Williams says of Graf. "She's always been so supportive. I know her husband, Andre [Agassi], who has been incredibly supportive. I feel that love and support. I really love that, when someone is trying to do the best that they can, that someone as great as Steffi is there to be supportive and be happy for the next person."

Patrick

Graf and Williams competed in two different eras, but some athletes just seem like they would have been a star regardless when they played.

"You can't help but admire her," John Isner, the top-ranked American male, says. "She's 33 or 34. She's completely dominant. It's amazing. It's a testament to how much she hates to lose and how hard she works. She really wants to cement her legacy. You can argue if she wins this U.S. Open, she's the greatest female athlete ever. There's a lot riding on this tournament."

Madison Keys, 20, the second-seeded American woman at No. 19, had not turned 1 when Williams turned pro. Williams beat a 17-year-old Martina Hingis for her first major in 1998. She beat a 21-year-old Garbiñe Muguruza to win Wimbledon in 2015

"I admired her growing up," says 21-year-old Monica Puig of Puerto Rico. "She was very powerful, very dominant and so strong. We're both very strong athletes. It was something I could look up to."

Serena and Venus have never been afraid to voice their opinions on civil rights and other political issues. This year, Williams ended a 14-year boycott of the Indian Wells Masters after the sisters endured racist comments in 2001.

Serena Vika Maria

"I look at someone like Althea [Gibson] and Zina [Garrison]," Williams says. "Let's face it, I have it a lot easier than them. There are so many barriers that have been broken. When I look at it in that point of view, that aspect, a whole weight is like lifted off my shoulders. I feel like I have nothing to complain about. I'm doing well and I'm really happy to be here."

She is still here. At 33. Having arguably the best season in tennis history.

"I have always dreamt of winning the Grand Slam," she says. "Again, it was just a dream. I never thought I would be close to doing something like that."

How about doing it well past your 33rd birthday?

Serena Williams has come a long way from the loss to Spîrlea at 16. So much so, she has a fuzzy memory of her first match at Arthur Ashe Stadium.

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-- Follow Jeffrey Eisenband on Twitter @JeffEisenband.

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