Serena Williams heads to Wimbledon halfway to a Grand Slam.

If it were up to her, no one would notice.

Williams prefers to downplay her chances of becoming the first tennis player in more than a quarter-century to win all four major tournaments — Australian Open, French Open, Wimbledon, U.S. Open — in the same season.

"I haven't done well at Wimbledon recently, so that's the only one that's kind of eluding me," Williams said, managing to keep a straight face and perhaps hoping to convince herself as much as anyone who might be listening. "So I'm trying to get to that one, at least make it deep in the second week of that tournament."

When play begins at the grass-court Grand Slam tournament Monday, Williams will be ranked No. 1, and seeded No. 1, and there is zero doubt that she is far and away the best tennis player on the planet at the moment. Indeed, she might very well be the best in history, a debate that can never be settled on a court, of course.

Already the Year of the Triple Crown in horse racing, 2015 could wind up being the Year of the Grand Slam in tennis and golf, with Jordan Spieth halfway to a 4-for-4 calendar year at his sport's major championships.

In tennis, only two men and three women have ever done it.

The last man was Rod Laver in 1969. The last woman was Steffi Graf in 1988.

"Why not?" said Williams' coach, Patrick Mouratoglou. "That's probably the most difficult thing to do in tennis. But it's possible."

There are others who could win Wimbledon, of course, challengers such as 2004 champion Maria Sharapova, two-time winner Petra Kvitova or 2013 runner-up Sabine Lisicki.

But as 18-time major champion and ESPN analyst Chris Evert put it when discussing Williams: "I mean, it's all up to her. When she is at her best, she is better than anybody else."

With a versatile and dangerous serve, and powerful groundstrokes, Williams' game translates quite well to the slick surface at the All England Club, where she has won the championship five times: 2002, 2003, 2009, 2010 and 2012. She also was the runner-up twice.

And yet, here is what Williams had to say shortly after winning the French Open for her 20th Grand Slam trophy and third in a row: "To be perfectly honest, I've never really liked grass, and I just don't know how I've done so well on it."

On her past two trips to Wimbledon, Williams bowed out in the fourth round in 2013, and the third round in 2014.

"The monkey's on my back. ... I just consistently do terrible there," Williams insisted, in just a bit of hyperbole.

"Now that it's a slower surface," Williams said, "it'll help me out a little bit."

Seems safe to say, actually, the speed doesn't matter.

Nor does the opponent.

What's really important when it comes to the 33-year-old Williams is how she's playing and if she is motivated to win.

As she showed during her comeback-filled run at Roland Garros, she can summon the skill and the will to turn any match in her favor, even on her worst days.

"Serena has seemed late in her career ... to be mentally tougher than she's ever been," said John McEnroe, a seven-time major champion who will be analyzing Wimbledon matches for ESPN.

A year ago at the All England Club, Williams departed under odd circumstances. She lost in the third round of singles to 25th-seeded Alize Cornet, then pulled out three games into a doubles match after appearing disoriented. Williams later blamed an illness.

She has not lost at a Grand Slam tournament since.

That's a 21-match winning streak, from New York last September, to Melbourne in January, to Paris this month. Williams is the first woman to win three consecutive majors since — big surprise here — she took four in a row for a self-styled "Serena Slam" in 2002-03.

As for the possibility of completing a true Grand Slam or eventually surpassing Graf's total of 22 majors, Williams is not all that keen about contemplating such milestones.

"I'm still playing, and when you're still playing, you're not thinking, 'Well, I'm here in the history books, and soon I'll be there.' Because then you've become really satisfied," she said. "And seeing that I'm the kind of person that I want to continue to play well, and I want to continue to win matches, I don't want to be satisfied. I want to keep going."

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