Davis Cup giants the United States and Australia breezed through the first qualifying round, but there was heartbreak for Great Britain as Japan made a thrilling comeback to win 3-2.
The Brits were up 2-1 but were eventually toppled by Japan, with former world number four Kei Nishikori sealing the win in a dominant performance over Billy Harris.
Australia, with their 28 Davis Cup titles, proved too strong for Sweden, with Alex de Minaur and Aleksandar Vukic securing singles wins, followed by a doubles victory from Matthew Ebden and John Peers.
The USA were also clinical, sweeping Taiwan 4-0, with Austin Krajicek and Rajeev Ram wrapping up the tie in doubles.
Denmark mounted an inspiring 2-0 comeback against Serbia, with Holger Rune and Elmer Moller leading the charge to secure the win.
The second round will see exciting matchups, including the Czech Republic vs. the USA, and a showdown between Spain and Switzerland.
