Coco Gauff will become the new World No.1 doubles player Monday when the rankings are released. She will become the 46th player to achieve this feat and the 11th American woman.

Gauff reached this milestone by winning the National Bank Open on Sunday with compatriot Jessica Pegula. Together, they outlasted Nicole Melichar-Martinez and Ellen Perez 6-4, 6-7(5), [10-5].

For Gauff and Pegula, it was their second title at a WTA 1000 tournament this season. In February, they won the Qatar TotalEnergies Open in Doha.

"Being No.1 is pretty cool," Gauff said in her post-match press conference. "I have no words. ... I didn't really know it was coming this week and what I had to do. But [Pegula] told me yesterday.

"As a kid, I'm going to be honest with you, I didn't even know there was separate rankings for singles and doubles. But when I got on tour and when I realized I could do well in doubles, yes. ... I wanted to. I mean, who wouldn't want to be No.1 in anything?"

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Gauff has had several other standout results in doubles over the past 12 months, including reaching two Grand Slam finals at the US Open in 2021 (with Caty McNally) and earlier this season at Roland Garros (with Pegula). Gauff also reached the final at the Porsche Tennis Grand Prix in Stuttgart alongside partner Zhang Shuai.

At 18 years and 154 days old come Monday, Gauff is the second-youngest player in history to earn the doubles No.1 ranking (which was introduced on Sept. 10, 1984) sitting behind Martina Hingis who was 17 and 251 days when she clinched the top spot in June of 1998. 

No.3 seeds Gauff and Pegula had to go down to the wire before winning Sunday’s final. After falling behind 3-0, Gauff and Pegula excelled on return as the first set progressed, winning six of the next seven games to take the one-set lead.

Melichar-Martinez and Perez held firm in the second set, saving three championship points at 5-4 and three more at 6-5. The unseeded duo then grabbed the tiebreak after a Perez backhand return winner found the baseline, and a decisive match-tiebreak would decide the victors.

Bold play at net by Perez led her team back from 6-2 down to 6-5 in the match-tiebreak. However, Gauff and Pegula stayed solid, and a volley winner by Gauff gave her pairing a seventh championship point at 9-5. A Pegula forehand forced an error to clinch the title and the World No.1 ranking for Gauff.

Just like Gauff, whose accolades are provided above, Pegula has also had a breakthrough season in doubles. Toronto marks Pegula’s fourth career doubles title, her third this season, and her second in two weeks. Pegula won the title in Washington, D.C. last week paired with Erin Routliffe.

Pegula, who is already a Top 10 singles player, will make her Top 10 debut in the doubles rankings on Monday.

"I'm so glad that I could help [Gauff] get there today," Pegula said. "I think we're No. 1 in the Race and the top two Americans in singles. So it's been a pretty cool little journey that we're on together, even though I'm ten years older," she added with a laugh.