Wishaya Trongcharoenchaikul and Palaphoom Kovapitukted lost their doubles contest as Thailand went down 3-0 to Denmark in their Davis Cup World Group 2 first round tie in Kolding on Saturday.
The Thai pair were in a must-win situation after both Wishaya and Kasidit Samrej lost their singles matches on Friday.
However the Danish combination of Benjamin Hannestad and Frederik Nielsen proved too strong for the Thai players as they took the match 6-3, 6-1 and claimed an unassailable 3-0 lead.
Nielsen, 37, is a former Wimbledon doubles champion. He won the title in 2012 with Britain's Jonny Marray.
Thailand will now have to compete in the play-offs next year with their opponents yet to be determined. They need a win to stay in World Group 2.
On Friday, Thailand's No.1 Wishaya, who is ranked 767th, lost the opening singles match against No.1,097-ranked Christian Sigsgaard 6-3, 6-2, while No.1,136 Kasidit went down to No.905 August Holmgren in a hard-fought three-set match 3-6, 7-5, 6-2 on the indoor hardcourt at Sydbank Arena.
Thailand and Denmark had never met before in the Davis Cup.
In Oslo, world No.10 Casper Ruud put Norway on the brink of a victory against Uzbekistan in the World Group 1 play-offs with a 6-3, 6-3 win over Khumoyun Sultanov on Friday.
Norway, who are in the World Group play-offs for the first time since 1995, took a 2-0 lead over Uzbekistan after Ruud beat the lowly-ranked Sultanov in just over an hour, while Viktor Durasovic sealed a 6-4, 6-4 win over Denis Istomin.
The teams playing in World Group 1 are bidding for a place in the 2022 Davis Cup qualifiers, a step closer to the Finals. bangkok post/reuters