Barbora Krejcikova doubled up at Roland Garros, as the 2021 women's singles champion paired with her long-time partner Katerina Siniakova to win the women's doubles title as well.

The No.2-seeded Czechs claimed the French Open women's doubles title for the second time after dispatching No.14 seeds Bethanie Mattek-Sands of the United States and Iga Swiatek of Poland, 6-4, 6-2.

"Of course, I feel amazing," Siniakova told the media, in the team's post-match press conference. "I'm really happy that we did it. I think we played great. We're really communicating really well. I think it's working."

Read more: From Novotna to Navratilova, French Open champ Krejcikova guided by Czech greats

Krejcikova and Siniakova have now won three Grand Slam women's doubles titles in their careers. They triumphed in Paris for their first crown in 2018, then quickly followed up with the Wimbledon title the very next month.

This, however, was the team's first trip back to the Grand Slam winner's circle since then. The Czech duo had finished as runners-up to Elise Mertens and Aryna Sabalenka at this year's Australian Open, but they went one further on the clay courts of Paris with their one-hour and 14-minute victory over Mattek-Sands and Swiatek.

The win completes an extremely triumphant fortnight for Krejcikova, who defeated Anastasia Pavlyuchenkova for the women's singles title on Saturday. Krejcikova is the first player to win both the singles and women's doubles title at Roland Garros since Mary Pierce achieved the feat in 2000.

Krejcikova also becomes the first player to sweep both of those events at any Grand Slam tournament since Serena Williams pulled it off at 2016 Wimbldon. As a result, Krejcikova will return to WTA Doubles World No.1 on Monday.

"Yesterday, so many emotions and everything," Krejcikova said. "I didn't really sleep well. I woke up in the morning and I felt really tired."

"I actually went really relaxed today when I went on court," Krejcikova continued. "I was just trying to really support my partner."

"I'm just really happy," Krejcikova added. "I'm really thankful to [Siniakova] that she was there, that she was standing next to me. It felt a little bit easier than yesterday. I'm just really happy that we have another title, and looking forward we're going to continue with our cooperation in Wimbledon and also for the Olympics. I hope there's going to be a bright future for us."

Krejcikova and Siniakova's surge to the top of the game was presaged when they won the Roland Garros junior doubles title in 2013 -- the first of the three straight junior Grand Slams they would win as a duo.

"If I remember right, it was a little bit lucky, no?" Siniakova recalled about their start in the juniors. "We started to play actually here at Roland Garros because we couldn't find [partners]. We won it. From that time we decided to play with each other because it went really good.

"Then we won Wimbledon junior title, then US Open. So it was a really amazing year. We really enjoyed it. From that time, it's a long journey, but I think we did a really great job. We both keep fighting. We find our way to pro tennis."

From their junior success, the pair of 25-year-olds have established themselves as one of the elite WTA doubles teams, and they proved it once more in Sunday's final, where they won 81 percent of their first-service points and converted five of their seven break points.

It was still a breakthrough week for Mattek-Sands and Swiatek, as "Team TekTekBoom" made it all the way to the final in just their third tournament as a tandem. In fact, this was the first Tour-level doubles final of Swiatek's career.

However, the American-Polish pair, who defeated No.1 seeds Hsieh Su-wei and Elise Mertens in the third round, could not get past the Czechs in the final.

As a result, Mattek-Sands's 5-0 undefeated streak in Grand Slam women's doubles finals has come to an end. Mattek-Sands still has an exceptional record at Roland Garros, having won the women's doubles title two times alongside Lucie Safarova, in 2015 and 2017.

Krejcikova and Siniakova charged to an early 4-0 lead to start the clash, sweeping past Mattek-Sands and Swiatek with an array of superb volleys and pristine returns.

At last, Swiatek was able to get her team on the board by holding serve for 4-1, and she grasped one break back with a winning volley to pull her squad within 5-3.

However, Krejcikova would not relent during her victorious weekend, as the newly-minted Roland Garros singles champion held at love to close out the opening frame.

A flurry of three straight breaks in the second set ended with a Krejcikova return winner putting her team ahead 3-2. From that point forward, Siniakova dominated at net with volleying mastery, clinching a second break and a 5-2 lead for the No.2 seeds.

With Siniakova serving for the match in that game, it was Krejcikova’s chance to take charge at the net, slamming putaways to reach triple championship point. On their second opportunity, Siniakova knocked off a backhand winner to wrap up the win and make the Czechs Grand Slam champions once more.

"I think we're going to have a dinner together this evening," Krejcikova said. "We will have a little glass of champagne. I already said I don't really drink but I think it's a time to actually celebrate it. I think we're going to really enjoy."

Krejcikova defeats Pavlyuchenkova for 1st singles Slam: Roland Garros Highlights