When Shuko Aoyama and Ena Shibahara first teamed up in 2019, the Japanese duo were at different stages of their careers. Aoyama was an established presence on the doubles circuit, where she reached 18 WTA finals over the past nine years with 11 different partners, but she had yet to win a title above 250 level. Shibahara, the 2016 US Open girls' doubles champion with Jada Hart, was a pro tour rookie fresh out of college, where she studied sociology at UCLA between 2016-18.

But as a pair, they have enjoyed sustained success since. They have collected eight titles together, which also comprise an eight-match winning streak in WTA finals. Five of those trophies came in a career-best 2021 season, including their biggest to date in Miami, and have sealed a debut appearance for both at the WTA Finals.

Shuko Aoyama and Ena Shibahara hold their champions' trophies after the doubles final at the Yarra Valley Classic.

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First quarter: Race leaders after winning streak

Aoyama and Shibahara began the year with a statement of intent. An 11-match winning streak took them through two consecutive titles in Abu Dhabi and the Yarra Valley Classic, all the way to the Australian Open quarterfinals, where it took eventual champions Elise Mertens and Aryna Sabalenka to halt them.

Road to WTA Finals, singles

Road to WTA Finals, doubles

The hot streak was a triumph of clutch play as well as dominant games. In their first match of the season in Abu Dhabi, Aoyama and Shibahara fended off four match points against Andreja Klepac and Marta Kostyuk. In the Yarra Valley Classic semifinals, they had to save six against Nicole Melichar-Martinez and Demi Schuurs. And in the second round of the Australian Open, they overturned one to beat Lizette Cabrera and Maddison Inglis.

Champions Corner: How Aoyama and Shibahara got out of their comfort zone to win Miami

Three first-round losses in Adelaide, Doha and Dubai constituted a surprising dip in form, but Aoyama and Shibahara roared back to life in Miami to capture a first WTA 1000 title, defeating Hayley Carter and Luisa Stefani in the final.

This extended the pair's season record to 15-4 - and ensured that, after the first quarter, they were perched at No.1 in the Race to the WTA Finals.

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April to July: Clay dip, grass surge

Clay has historically been Aoyama's Achilles heel. The 33-year-old has yet to reach a WTA final on the terre battue. Shibahara has accomplished that, at Bogota 2019 alongside Carter, but only once. In 2021, the pattern didn't change significantly. Despite a semifinal run in Rome, the pair finished the clay season with a meagre 3-4 record.

But on slick grass, which rewarded their fast-paced style, Aoyama and Shibahara were rejuvenated. An eight-match, 16-set streak took them to their fourth title of the year in Eastbourne and then to a career-best Grand Slam showing at Wimbledon, where they made the semifinals before falling to eventual champions Mertens and Hsieh Su-Wei.

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Hardcourt return: Olympic disappointment, American resurgence

Despite their strong lead-in form, there was to be no triumphant homecoming at the Tokyo Olympic Games. Aoyama and Shibahara were bounced in the first round by eventual silver medallists Belinda Bencic and Viktorija Golubic 6-4, 6-7(5), [10-5].

The Olympic hangover continued with early losses in Montréal and Cincinnati, but Aoyama and Shibahara got their groove back in Cleveland - coincidentally, the same tournament at which Shibahara made her WTA main-draw debut in singles - where they captured a tour-leading fifth title of the year.

At the US Open, for the third time in four majors, it took the eventual winners to stop Aoyama and Shibahara, who fell to Samantha Stosur and Zhang Shuai in the third round. They have since backed that up with a run to the Indian Wells semifinals, falling again to Hsieh and Mertens.