Spain lead Japan in their Fed Cup qualifying clash as Naomi Osaka suffered a shock defeat to Sara Sorribes Tormo at La Manga Club in Murcia.
Sorribes Tormo put Spain 1-0 up on the famous clay court, defeating former world number one Osaka 6-0, 6-3.
Carla Suárez Navarro then overcame Misaki Doi 6-3, 6-4 to see Spain go into the second day of competition with a 2-0 lead.
Osaka will meet Suárez Navarro while Doi comes up against Sorribes Tormo, with a doubles rubber scheduled if a decider is needed.
Switzerland also managed to win both of their matches, with Jil Teichmann battling past Leylah Annie Fernandez of Canada 7-6, 6-4 at Swiss Tennis Arena in Biel.
World number five Belinda Bencic then comfortably beat Gabriela Dabrowski 6-1, 6-2.
The Netherlands and Belarus ended the first day of competition with scores even.
Kiki Bertens gave the Dutch team the lead after coming back from one set down to win 6-7, 6-2, 6-1 against Aliaksandra Sasnovich at Sportcampus Zuiderpark in The Hague, before Belarus fought back through Aryna Sabalenka, who overcame Arantxa Rus 6-2, 6-3.
Romania's clash with Russia at Sala Polivalenta Cluj-Napoca also sits at 1-1, with Ekaterina Alexandrova putting the visitors 1-0 up by defeating Elena Gabriela Ruse 6-1, 6-4.
Ana Bogdan then drew Romania level following a close 6-3, 6-7, 6-1 victory against Veronika Kudermetova.
The United States took on Latvia at Angel of the Winds Arena in Washington, taking a 2-0 lead.
Twenty-three-times Grand Slam winner Serena Williams came up against Jelena Ostapenko, edging past the player, 16 years her junior, 7-6, 7-6.
Sofia Kenin, winner of this year's Australian Open, then comfortably beat Anastasija Sevastova 6-2, 6-2.
The reverse rubbers are due to take place tomorrow, followed by a deciding doubles match if necessary.
