Diede de Groot is trying to join the most exclusive club in tennis.
The wheelchair tennis world No. 1 from the Netherlands arrived at the Tokyo Paralympics having already won the Australian Open, French Open and Wimbledon this year.
She beat Momoko Ohtani in the quarterfinals of the Paralympic tournament on Tuesday to advance to the semifinals at the Tokyo Games and remain on track for the rare Golden Slam: a calendar Grand Slam that includes an Olympic or Paralympic gold medal.
Tennis legend Steffi Graf is the only player to have done it. Graf won the women's title at all four major tournaments in 1988 and also won a gold medal for West Germany at the Seoul Olympics.
De Groot would need to win Paralympic gold in Tokyo and then the U.S. Open title later this month to become the first women’s wheelchair singles player to achieve the Golden Slam. Australian wheelchair tennis quad singles men’s player Dylan Alcott also has a chance.
Men's world No. 1 Novak Djokovic arrived at the Tokyo Olympics last month with a chance to complete the fourth leg of the Golden Slam but was upset by Alexander Zverev in the semifinals.
“Really, he's just human," de Groot said after her win on Tuesday. "All of us are human and so is Djokovic. Even though he’s the best player at the moment, you can still lose a match.
"And the same goes for me. Even though I'm on top of the rankings, anything can happen. It's a difficult sport, so I'm just trying to play my game and focus on myself.”
De Groot beat Ohtani 6-3, 6-2 in their quarterfinal matchup, but it was not smooth sailing despite the straight-sets scoreline. The Dutchwoman raced out to 5-0 leads in both sets only to see the Japanese stage several brief rallies.
“My momentum or my focus went down a little bit, so even though I was five up she came back 5-2, and also the same in the first set," de Groot said. "It was good, but also there are more improvement points.”
De Groot was born with a right leg that is much shorter than her left. She began playing wheelchair tennis at age 7 and is competing in the Paralympic singles tournament for the second time. De Groot finished fourth at the Rio Games, where she earned a silver medal in the doubles competition.
De Groot's next match will be against Great Britain's Jordanne Whiley in the semifinals. If she gets through that, world No. 2 Yui Kamiji could be waiting in the final.
She will be favored in both the semifinal and final — if she gets there — because of the run of success she's been on recently.
De Groot won last year's U.S. Open which, when combined with her major victories this year, means she currently holds all four Grand Slam titles. She's 24-1 overall this season, according to the International Tennis Federation.
She met Djokovic after their respective wins at Wimbledon, a brief encounter of two players at the top of their games.
“He was very excited for wheelchair tennis," she said. "He was actually in a little bit of a hurry, but as soon as he saw me, and I wanted to take a picture with him, he dropped everything. He stood still to really talk with me, and say how much he appreciates wheelchair tennis and how much he respects it. So it was a nice conversation.”
Even without the pressure of the Golden Slam on the line, the spotlight is on de Groot in Tokyo as the premier player in her sport.
“It's always a difficult situation," she said last week. "On one hand it means that you have a chance. Being maybe No. 100 in the world, it doesn't give you a very big chance of winning gold. But being No. 1 gives you a big chance.
“But there is a lot of pressure. I can't deny that I do feel the pressure, but also I'm just enjoying myself and playing round by round.”