(Reuters) -Davis Cup heavyweights Australia and the United States eased through the first qualifying round on Saturday but Britain were knocked out as Japan hit back from 2-1 down to win 3-2, while Denmark staged a dramatic comeback to overcome Serbia.

Great Britain face a Davis Cup relegation play-off after losing their first-round tie 3-2 against Japan. With the tie level at 1-1 after Friday's opening day, Britain took the lead when Neal Skupski and Joe Salisbury won Saturday's opening rubber 7-6 7-6 against Yosuke Watanuki and Takeru Yuzuki.

Great Britain will face a relegation play-off in the Davis Cup after their makeshift team failed to make the cut and were beaten 3-2 by Japan. While Jacob Fearnley gave the side hope, this was quickly extinguished as a poor end to Saturday saw them slump out.

Alex Michelsen gave the United States a 2-0 lead over Taiwan on his Davis Cup debut in the first round qualifiers on Friday, while Jacob Fearnley also impressed in his first appearance in the competition to pull Britain level with Japan.