MIAMI, FL, USA -- Elise Mertens and Aryna Sabalenka are one win away from a perfect March on the doubles court.

The Indian Wells champions notched their ninth consecutive match victory in the semifinals of the Miami Open on Friday, squeaking past the wild card team of Victoria Azarenka and Ashleigh Barty, 7-6(6), 7-5, in an hour and 40 minutes of tense action.

Read more: Mertens, Sabalenka match energies as Sunshine Double edges closer

Mertens chalked up their latest victory to their ever-increasing workload. "We’ve played, of course, a lot of doubles matches these last couple of weeks, so I think that really was the key for us," said the Belgian. "To know what we’re doing, when to switch, and even to pump each other up when it was getting tighter."

"Of course we were playing against two great players, Barty’s still in singles," Mertens continued. "It was a really tough match."

Mertens admitted that completing the 'Sunshine Double' of winning Indian Wells and Miami back-to-back would mean "a lot" to her and her Belarusian partner. "Singles or doubles, for me it doesn’t matter -- a title is a title. Of course, if we have the opportunity, I really hope we take it."

To take it, Mertens and Sabalenka will have to defeat reigning Australian Open champions Samantha Stosur and Zhang Shuai in the final. No.6 seeds Stosur and Zhang overcame the 8th-seeded Chan sisters, Hao-ching and Latisha, 6-7(6), 7-5, [10-5], in a tight semifinal battle that took nearly two hours on Friday night.

In the first semifinal, Azarenka and Barty raced out to a 3-0 lead before Mertens and Sabalenka won three games in a row to level the set at 3-3. Barty then led her team to another break and a 4-3 lead, but at 5-4, Azarenka was unable to serve out the set, as a Sabalenka backhand pass queued up break point, and Azarenka double faulted to cede her team’s advantage. 

The teams advanced to the tiebreak, where a long volley by Barty gave Mertens and Sabalenka a 6-3 lead and three set points. All three were saved, the third with a Barty overhead, but the Australian ended a rally with a netted forehand, setting up a fourth set point. There, powerful groundstrokes by Sabalenka helped her team close out the tiebreak 8-6.

Azarenka dropped her serve in her first service game of the second set, giving Sabalenka and Mertens the early break, which they held onto through 5-4. With Sabalenka serving for the match, her team saved three break points from 0-40, setting up deciding point, which was also match point. But Sabalenka sent a forehand long, letting Azarenka and Barty level at 5-5.

But Sabalenka rebounded, crushing more powerful groundstrokes to lead her team to another break of the Azarenka serve and a 6-5 lead. Mertens took a turn to serve out the match, and quickly reached triple match point. Azarenka ended a rally with a long backhand on the first match point of that game, giving Mertens and Sabalenka another win.

In the late semifinal, Stosur and Zhang exchanged breaks with the Chan sisters three times before advancing to the tiebreak, with Hao-ching sticking a volley to stave off a set point at 5-4. The Chans survived three more set points in the tiebreak, punching volley winners with ease to reel off the final five points and steal the first set from 3-6 down in the breaker.

The sisters hailing from Chinese Taipei held an early break at 2-0 in the second before a Zhang overhead allowed her team to break right back for 2-1. The teams stayed on serve until 5-5, when Stosur crushed a return winner down the line on deciding point to break for 6-5. Zhang then held serve to level the match at one set apiece and bring up a match tiebreak.

Stosur brought her game to an exceptional level in the match tiebreak, blasting three return winners in the first nine points, then slamming an ace to lead 7-4. Zhang fired a fierce forehand to reach 8-4, and the Australian/Chinese team reached match point at 9-5 after a winning backhand volley by Stosur. There, a netted return from Latisha Chan ended the engrossing encounter.