Klineman won Tokyo 2020 gold with April Ross, and has returned to the World Championships in Mexico four months after giving birth.

She lost her first match with Harward at the Volleyball World Beach Pro Tour Elite 16 event in the French capital Paris, but overcame a tough opening challenging at the World Championships in the form of last year's bronze medallists Svenja Müller and Cinja Tillmann of Germany in Pool K.

The American duo took the first set 25-23 and dominated the second 21-14 for an impressive win at the Plazas de Toros in Tlaxcala.

Klineman contributed 19 points in the match, and expressed her satisfaction at the strong start to the tournament.

"Germany are a great team and we’ve been preparing really hard for the last two months," she said.

"Paris didn’t go the way we wanted and we’re just excited to have more opportunities to compete together.

"We have a tough pool.

"Brazil and China are both really good teams and we’re not expecting anything to be easy."

China's Dong Jie and Wang Fan won the other opening Pool K match, beating Brazil's Tainá Silva Bigi and Victória Lopes 21-19, 21-19 in Tlaxcala.

The other two American pairs in the women's tournament also began with victories.

Julia Scoles and Betsi Flint overcame Austria's Dorina Klinger and Ronja Klinger 21-17, 21-14 in Pool J, and in Pool B at the Plazas de Toros in Huamantla, Kristen Nuss and Taryn Kloth earned a fine 21-15, 21-15 win against Japan's Akiko Hasegawa and Yurika Sakaguchi.

Olympic silver medallists Taliqua Clancy and Mariafe Artacho del Solar of Australia started with a 21-16, 21-12 success against Dominican Republic's Bethania Almánzar and Julibeth Payano in Pool E, while Switzerland's Tokyo 2020 bronze medallist Anouk Vergé-Dépré with new partner Joana Mäder came from behind to beat Thailand's Taravadee Naraphornrapat and Worapeerachayakorn Kongphopsarutawadee 22-24, 21-15, 15-12 in Pool L.

In pool A, defending champions Duda and Ana Patrícia of Brazil began with a routine 21-5, 21-17 win against Chile's María Rivas and Chris Vorpahl.

On the second day of the men's tournament at the World Championships, the 2013 world champions Alexander Brouwer and Robert Meeuwsen started in impressive fashion against Thailand's Poravid Taovato and Pithak Tipjan in Pool J, triumphing 21-14, 21-15.

Apizaco, halfway on the road between Mexico City and the port of Veracruz. is the other host city for the Beach Volleyball World Championships, and Olympic bronze medallists Cherif Younousse and Ahmed Tijan of Qatar began their campaign with a straight-forward 21-7, 21-4 win against Guatemala's Andy Blanco and Luis Garcia.

In a competitive Pool K in Huamantla, Argentina's Nicolás Capogrosso and Tomas Capogrosso gained revenge for their defeat in last year's South American Games final to Chile's Marco Grimalt and Esteban Grimalt with a 24-22, 21-16 victory, and Poland's Bartosz Łosiak and Michał Bryl beat France's Rémi Bassereau and Julien Lyneel 21-18, 21-14.

The pool stage of the FIVB Beach Volleyball World Championships is due to finish on Monday (October 9), with the top two from each pool advancing to the round of 32 along with the four best third-placed teams.

The other eight third-placed teams require a playoff to decide the remaining four places.

The men's and women's winners are set to be allocated the first Olympics quota places for Paris 2024 in beach volleyball after that reserved for host nation France.