The No. 13 seeds saved three match points to win a thrilling women's doubles final at the US Open on Sunday afternoon, defeating No. 2 seeds Timea Babos and Kristina Mladenovic in the final, 3-6, 7-6, 7-6.
Contesting their first Slam final as a duo, the No.13 seeds didn't drop a set en route to the final and beat the reigning Australian Open champions after two hours and 30 minutes under the Arthur Ashe Stadium roof.
Barty and Vandeweghe first came through a crucial hold of serve in the 10th game of the second set, where they rallied from 15-40 down, to knot the action at 5-5 and save two championship points.
Over an hour later, having seen their break advantage slip away in the decider, the American-Aussie pair saved another championship point in the ensuing tiebreak, on their way to victory.
"There were so many ebbs and flows through the match. I told Ash, 'Listen, there's no one I'd rather be out here with than you right now. I believe in you. We're going to get this done,'" Vandeweghe said, after the match.
"We've been talking about this moment. For me, personally, I wouldn't have dreamed this possible at the start of the week, of how I entered into the event, not even close to 100%. Even questioning if I was going to play the event. I definitely didn't think this was going to be a possibility. I'm so happy to be here now at the end, with a trophy."
"Obviously we've only played a handful of tournaments together this year, but we've had pretty good success right from the get-go. This last fortnight has been really fun on and off the court," Barty added.
"We've been relaxed. We're very hungry to go as deep as we could. It was really nice to be able to play a pretty clean tournament."
WHAT IT MEANS: Two pairs who've won some of the WTA's biggest trophies this year thrilled the fans inside Ashe in the fourth three-set women's doubles final in the past six years.
Babos and Mladenovic, chasing their second Slam after winning at the Australian Open, reflected on the part they played in a classic in their post-match press conference.
"I think it just slipped out of our hands in the second set, and then, after we were down big-time and we were really fighting till the end and this is why they are such a great team," Babos said, in defeat.
"I don't have regrets. We gave everything what we had. It was a great opportunity, but 100% sure that the way we play we will have a lot, lot, lot more."
Mladenovic added: "From both sides were some rallies, some lines, luckier shot here and there. It's all about this. It's the magic of tennis. I am only proud...and the way we played tonight was great."
For Barty and Vandeweghe, the Flushing Meadows victory marks their second title of the season: they had already triumphed this spring at the Miami Open.
"When you win, it's always going to propel you no matter what sector you're playing in. When you're winning, you're feeling good, you're confident in yourself, it's going to propel you forward," Vandeweghe said.
"I think it's finally the first time we've played together at a Grand Slam. I was just dying for it. She was great to play with for two weeks. I had an amazing time out there with Ash."
MATCH POINT: The first major title for both Barty and Vandeweghe will no doubt be sweet after several runner-up finishes. The two had previously combined for six runner-up finishes in women's and mixed doubles, respectively.