Before 2021, Hsieh Su-Wei and Elise Mertens were only familiar with each other as opponents. But they formed an unlikely team out of the ashes of two previous successful partnerships - and after a stuttering start, it paid off.

Hsieh and Mertens' season highlight was capturing the Wimbledon title - a third for Hsieh and first for Mertens - with one of the most memorable runs of the year. They also added the Indian Wells trophy to their haul, enabling Hsieh to seal her fourth WTA Finals qualification with her third partner (following Peng Shuai in 2013-14 and Barbora Strycova in 2019), and Mertens her third qualification with as many partners (following Demi Schuurs in 2018 and Aryna Sabalenka in 2019).

April to June: Match point issues and a slow start

For both Hsieh and Mertens, their previous partnerships had ended for reasons beyond their control. Barbora Strycova, who had won nine titles including Wimbledon 2019 with Hsieh, announced her pregnancy in March; Aryna Sabalenka and Mertens captured their second major trophy at the Australian Open, but the Belarusian stated afterward that she would be focusing on singles at Grand Slams.

At loose ends, Hsieh and Mertens joined forces for a collaboration that had a somewhat experimental air about it. This was certainly evident in their early days, during which they struggled to win matches - frequently from leading positions.

In their first match together, Hsieh and Mertens squandered four consecutive match points before losing 7-6(2), 4-6, [11-9] to Jelena Ostapenko and Anastasia Pavlyuchenkova in Madrid. In their second, they enjoyed a dominant start but fell in another match tiebreak 1-6, 6-4, [10-4] to Sharon Fichman and Giuliana Olmos.

Road to WTA Finals, singles

Road to WTA Finals, doubles

The third round of Roland Garros saw them blow a 5-1 third-set lead, and seven match points along the way, in a 5-7, 6-4, 7-5 loss to Bethanie Mattek-Sands and Iga Swiatek. In the Birmingham semifinals, they led 6-3, 5-0 and held five match points before contriving to lose to Ons Jabeur and Ellen Perez 3-6, 7-5, [10-3].

Five tournaments in, and Hsieh and Mertens had little to show for their nascent partnership but a series of somewhat disastrous collapses.

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Wimbledon: Victorious vindication

If Hsieh and Mertens were going to turn their fortunes around anywhere, Wimbledon was the ideal tournament. It was historically Hsieh's best major - she had won it twice previously with both Peng and Strycova - and grass was a perfect fit for both her array of slices and Mertens' flat hitting.

The quality they displayed en route to the final, particularly in a 6-4, 1-6, 6-3 semifinal thriller over Shuko Aoyama and Ena Shibahara, bore this out. And against Veronika Kudermetova and Elena Vesnina, Hsieh and Mertens exorcised their match point demons in style.

This time, it was the Chinese Taipei-Belgian duo pulling off the miracle comeback. They saved two championship points down 4-5 in the second set and triumphed in a top-quality overtime match, 3-6, 7-5, 9-7.

"It was definitely disappointing that we had some matches that we didn't finish, couldn't finish some chances," Mertens said afterward. "But I think the best thing to do is to learn from it. If you keeping negative about it, you're not going to go any further, you're not going to go forward, not going to grow as a team."

Second half: Indian Wells stranglehold

Hsieh and Mertens were unable to add to their major tally at the US Open, where they fell 6-3, 7-6(1) to eventual runners-up Coco Gauff and Caty McNally in the quarterfinals. But historic success proved to be a good indicator again in Indian Wells. Between them, Hsieh and Mertens had owned recent editions of the tournament. Hsieh had been the 2018 champion with Strycova, and Mertens had succeeded her in 2019 with Sabalenka.

Champions Corner: Hsieh and Mertens unleash 'the dragon' to win Indian Wells

Together, naturally, they were unstoppable. In the second round, they took sweet revenge on Mattek-Sands and Swiatek, overturning a 1-6, 1-4 deficit en route to winning 1-6, 6-4, [10-8]. That was the only set they lost. Victory over Kudermetova and Elena Rybakina in the final sealed Hsieh's 30th WTA doubles title, Mertens' 14th, and the second as a team who had proved the worth of sticking at a task that had been initially frustrating.