What country was the first unseeded winners of the Davis Cup (an international team event in men's tennis)?

The Davis Cup is an annual international team event in men's tennis. Established in 1900 as the International Lawn Tennis Challenge, it is run by the International Tennis Federation (ITF), who describe it as the "World Cup of Tennis."

Croatia competed in its first Davis Cup in 1993 in Europe/Africa Group I semifinals beating Zimbabwe 3-2. In 1994 Croatia beat Portugal 4-0 in qualification round thus ensuring its first time appearance in World Group in 1995. Croatia lost in its debut from Germany and failed to qualify in the World Group again until 2002 where they beat Germany and earned its first quarterfinals. In 2005 Croatia won its first Davis Cup over Slovakia as the first unseeded nation to win the title. Croatia reached semifinals in 2009 but lost to Czech Republic 4-1. In 2016 Croatia reached the finals for the second time, again as unseeded nation, but lost to Argentina.