Asia Muhammad and Taylor Townsend captured their first title as a team after five years of an on-off partnership by upsetting Serena Williams and Caroline Wozniacki in the ASB Classic final.

AUCKLAND, New Zealand - Unseeded Asia Muhammad and Taylor Townsend denied Serena Williams the ASB Classic double, defeating the singles champion and Caroline Wozniacki 6-4, 6-4 in the doubles final.

Muhammad extends her unbeaten record in WTA doubles finals to 5-0, while doling out just the second doubles final defeat of Serena Williams's career following Carlsbad 1999, where Lindsay Davenport and Corina Morariu defeated Serena and elder sister Venus 6-4, 6-1.

For Townsend, who lost both of her previous WTA doubles finals - including last year's Auckland final alongside Paige Mary Hourigan to Eugenie Bouchard and Sofia Kenin - it is a maiden WTA trophy of any kind.

"I think we had a pretty solid game plan going into the match, and we managed our nerves and knowing who was on the other side of the net," Townsend said.

"[We were] not really getting too caught up in that, keeping our heads down and just playing and doing what we had been doing the entire tournament."

What Muhammad and Townsend lacked in their opponents' singles pedigree they made up for with experience and smartly executed aggressive tactics. In contrast to the first-time team of Williams and Wozniacki, the American duo have been playing together on and off since 2013, and have captured nine ITF titles together.

Throughout the match, they moved harmoniously with each other in perfect sync, both seeking to swarm the net as early and as often as possible to carve away exquisite, delicately angled volleys with lightning reflexes.

"We're really good friends off the court and I think that just helps while being on court," Muhammad added. "If we're not feeling something, we can just talk to each other pretty openly, or if someone is not doing something, we can get on them a little bit -- in a friendly way. I think it just helps a lot with our team dynamic."

Superb forecourt play from both garnered them the first break of the match, capturing the Wozniacki serve for 2-1 - and though a series of ferocious Williams returns broke Townsend back immediately, a Muhammad volley straight at Williams followed by a whipped forehand return from Townsend put the 2016 US Open quarterfinalists back in the lead with another break of Wozniacki.

This time, they navigated the danger on the Townsend serve with more success, Muhammad putting away a forehand volley on deciding point before the 28-year-old served out the opening set with classy deliveries two games later.

"We both like to come in, we both like to be at the net, and that's where we play our best, so that was really the ultimately game plan: to use our strengths, which is really what you have to do in doubles," assessed Townsend.

"That's what we tried to do the entire time. They're not going to give any free points or give the match, so we had to make sure that we executed the whole time."

Congratulations to @asiamuhammad and @TaylorTownsend !



They beat Williams and Wozniacki 6-4, 6-4 to become the new @ASB_Classic doubles champions! pic.twitter.com/Q5Bx6Oluda — WTA (@WTA) January 12, 2020

Muhammad would again excel in the second set: it was the doubles World No.64 who came up with a backhand return winner followed by cool-headed volleys, one off each wing, to seize the Wozniacki serve for a third time for 2-1.

Though Williams was also putting in an excellent serving performance, repeatedly rattling off holds by setting easy volley putaways for Wozniacki, the American was less sharp off the ground than she had been in defeating Jessica Pegula to win the singles title earlier, and the awkward, skidding shots she was dealt by her opponents frequently elicited errors.

Read more: Serena ends trophy wait in Auckland, fights past Pegula in final

But as the second set drew on, Muhammad and Townsend grew in stature. A bold serve-and-volley, executed brilliantly, by Muhammad staved off break-back point on her own serve in the fourth game; and when Townsend stepped up to serve for the championship, the 23-year-old came up with a marvelous smash, a forehand volley placed plumb on the sideline and a first ace before sealing the title with a service winner.

"I'm feeling pretty happy about the week and starting the year off really strong," Muhammad said. "We'll obviously try and play somewhere. I would've loved for us to play the Australian Open, but at the time, our rankings wouldn't have gotten us in there [together], so we'll just have to see where we end up."