NEW YORK, NY, USA -- No.4 seeds Elise Mertens of Belgium and Aryna Sabalenka of Belarus finished a brilliant season on American hardcourts by winning their first Grand Slam title at the US Open on Sunday, defeating No.8 seeds Victoria Azarenka of Belarus and Ashleigh Barty of Australia, 7-5, 7-5, to clinch the women’s doubles championship.

"I think from the start of the season, start of the year actually, well, we were, like, 'We're going to play together,'" Mertens said in their champions' press conference. "We didn't think we would achieve this big thing. Really happy about it, and I think we are growing as two doubles players playing together."

Mertens and Sabalenka pulled off an undefeated 10-0 streak in March to capture the “Sunshine Double” -- winning titles at Indian Wells and Miami back-to-back, including a 7-6(6), 7-5 win over Azarenka and Barty in the Miami semifinals.

The fourth seeds, who then went on to reach the Roland Garros semifinals and Wimbledon quarterfinals, pulled that form into the year’s last Grand Slam event to make their first-ever major final, where they edged Azarenka and Barty once more after one hour and 36 minutes of tense tennis.

"First time we played against them in Miami, I think, like the first three games was something crazy because Elise was telling me, 'Just cool down a little bit,'" Sabalenka admitted. "This time, I was just trying to focus on each point and try to bring my best on the court. I think it was a crazy good match today. Great level, good atmosphere."

On Arthur Ashe Stadium, the teams were evenly matched in service effectiveness, and Azarenka and Barty even had more winners and fewer unforced errors than the victorious team. However, the 8th-seeded team were undone by a 2-for-8 conversion rate on break points, while Mertens and Sabalenka won all four of the break points they held in the clash.

"I think maybe the consistency," Mertens responded, when asked about the key to the match. "I think we started off a little shaky with the returns. But after we tried to make those returns, tried to stay aggressive. [Sabalenka] made some amazing shots at some points."

Azarenka and Barty took the initial lead, after a big Azarenka backhand earned her team a break of Mertens’s serve, at love, to go up 3-1. But Mertens and Sabalenka immediately got back on serve, after Barty ended her next service game with a double fault. Sabalenka survived two break points on her serve in the following game, as the teams were on serve through 4-3.

Barty, who won the US Open women's doubles title last year with CoCo Vandeweghe, commandingly put her team up 5-4, holding at love with two consecutive aces. Sabalenka, though, withstood the pressure, holding serve for 5-5, then blasting big shots at the opposing team to earn break point in the next game, after Azarenka and Barty led 40-15 on Azarenka's serve. On that point, Barty pushed a volley wide at the end of a rally to cede the 6-5 lead to the No.4 seeds.

With Mertens serving for the set, strong shots from Azarenka brought her team to 0-30, but the Belgian rebounded to set point. Sabalenka netted a volley to squander that chance, but she recovered with a drop volley winner to line up a second set point for her tandem. There, Sabalenka knocked off an overhead winner to claim the opening frame.

After an early exchange of breaks to open the second set, Azarenka and Barty each found winners down the lines to jump to an 0-40 lead on Mertens’s serve at 4-3. The fourth seeds were able to fend off all of those chances, as well as a fourth break point which Mertens erased with a stirring backhand winner down the line. Two putaways by Sabalenka closed out that hold for 4-4.

Just as in the first set, the Azarenka service game at 5-5 proved critical. Once more, Mertens and Sabalenka fought back from 40-15 to deuce, at which point Azarenka fired an overhead into the net to find herself down break point. Again, Mertens and Sabalenka stayed perfect on break points, after an Azarenka backhand went wide to give up the service break.

Mertens reached championship point on her serve at 40-30 after a Barty return flew wide, and at that juncture, an astounding all-court point ensued, with the combatants flying around the court before Azarenka ended the rally, and the final women’s event of the tournament, with a long smash.