Up-and-coming Misaki Doi gave Japan a perfect start as they led 2-0 against Argentina on the first day of the Fed Cup World Group II play-off on Saturday.
The 20-year-old, who reached the third round at Wimbledon at her first attempt, whitewashed Maria Irigoyen 6-0, 6-0 in the opener of the best-of-five contest in the Japanese city of Kobe.
Ayumi Morita followed her with a solid 6-2, 6-3 victory over Mailen Auroux in the second singles.
After reverse singles matches on Sunday, Rika Fujiwara and Kurumi Nara will play the doubles against Irigoyen and Auroux.
The World Group II play-off was originally scheduled for April but the earthquake and tsunami and ensuing nuclear emergency in northern Japan forced its postponement.
The two countries have an even 3-3 record but Argentina have won the last three ties. The winners will be promoted to World Group II along with Belarus, Slovenia and Switzerland next year.