Well before they were Grand Slam singles champions, Ashleigh Barty and Barbora Krejcikova made their first big impressions lifting major doubles trophies.

Barty reached the 2017 French Open final with Casey Dellacqua, won the 2018 US Open title with CoCo Vandeweghe and made the 2019 US Open final with Victoria Azarenka.

Krejcikova won the 2018 French Open and Wimbledon championships with Katerina Siniakova, and three consecutive Australian Open mixed titles, with Andy Ram and Nikola Mektic.

That Barty (2019 French Open and 2021 Wimbledon) and Krejcikova (2021 French Open) would eventually break through in singles wasn’t terribly surprising.

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“I thought it was the reason Krejcikova won the French Open, because she had been there in doubles,” said Pam Shriver, a 22-time Grand Slam doubles champion. “That comfort zone, having been in those major quarters, semis and finals, helped her in Paris this year.

“Same with Barty. You can only act like you’ve been there – if you’ve been there.”

Doubles is an excellent training ground for strategy, and it often puts you in spots that are sometimes unusual in singles, i.e., the net. Volleying skills separate Barty and Krejcikova from many players and add to the pleasing (and successful) variety in their games.

While most of the attention at the Tokyo Olympics is focused on singles, doubles provides three times the opportunities to medal:

Women’s singles – gold, silver, bronze (3). Women’s doubles – two golds, two silvers, two bronze (6). Mixed – gold, silver, bronze (3).

Shriver has her own gold medal, from the Seoul, South Korea Olympics when she won doubles with Zina Garrison.

“When I think about playing with Zina, and my gold medal from 1988, it feels just the same as if it as from singles,” Shriver said. “It’s the same gold medal.”

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Safe to say, that’s how the doubles players still alive in Tokyo feel. We’re down to the semifinals in doubles and the mixed quarterfinals. Play in both disciplines begins Thursday in Tokyo.

As a public service to those who haven’t been following along at home, here are five compelling doubles storylines to savor:

1. Belinda Bencic seeking the double: The 24-year-old from Switzerland is the only woman alive in singles and doubles. The No.9 seed defeated Anastasia Pavlyuchenkova in straight sets to set up a semifinal encounter with Elena Rybakina. She and Viktorija Golubic are in the semifinals, where they’ll play the unseeded Brazilian team of Laura Pigossi and Luisa Stefani. The only player on the men’s side remaining in two draws is Novak Djokovic. The ATP’s World No.1 is playing mixed with Nina Stojanovic.

2. Elena Vesnina doing it again: The 34-year-old Russian – and mother of a 2-year-old daughter named Elizabeth –is the only player left in any draw with the chance to defend her 2016 Rio de Janeiro medal. Vesnina won doubles gold with Ekaterina Makarova, and now she’s half of an unseeded pair with Veronika Kudermetova. Bethanie Mattek-Sands won gold with Jack Sock in Rio, but lost in Tokyo’s first round with Andy Ram. Five years ago, Petra Kvitova won bronze – but fell in the second round to Alison van Uytvanck.

3. Krejcikova looking for gold: The first time they played together on the pro tour, Krejcikova and Siniakova made it all the way to the final of the $25,000 ITF event in Bad Saulgau, Germany. That was eight years ago and, after a series of other partners, this tandem seems to work the best. The two Czech players advanced to the final in Tokyo with a thrilling 6-3, 3-6, (10-6) super-tiebreaker victory over Veronika Kudermetova and Elina Vesnina.

4. Sakkari and Tsitsipas mixed favorites – Greece’s mixed powerhouse is now the team to beat after Vesnina and Aslan Karatsev knocked off the top seeds, Kristina Mladenovic and 39-year-old Nicolas Mahut of France.

 “It’s not so relaxed, because we both want to win,” Sakkari told the International Tennis Federation website. “We have a great chemistry on court, and I think our games also fit well to each other. We can really do some damage here.”

The No.2-seeded Sakkari and Tsitsipas play Barty and John Peers in a match that features two Top 20 WTA players.

5. More marquee women – Also left in the mixed draw: 2020 French Open champion Iga Swiatek and 2021 French Open finalist Anastasia Pavlyuchenkova. Swiatek and Lukasz Kubot face Vesnina and Karatsev, while Pavlyuchenkova and Andrey Rublev take on the Japanese team of Ena Shibahara and Ben McLachlan.