Chief executive Roger Draper has promised a full internal review from the Lawn Tennis Association following Great Britain's latest Davis Cup humiliation.
John Lloyd's future as team captain has come under the spotlight after Lithuania inflicted a fifth consecutive defeat on his ailing side in a Europe-Africa Zone Group II clash over the weekend.
"I share the deep disappointment and frustration at this result. Five defeats in a row is unacceptable," Draper told the LTA's official website.
"So I have asked the player director, Steven Martens, to review last week's performance and result, and report back to me and the main board as soon as possible.
"That review needs to be swift and decisive as it is clear some real improvements need to be made."
James Ward and Dan Evans were expected to complete a straightforward victory after GB had moved 2-1 ahead after Saturday's doubles.
However, Ward was beaten in straight sets by Ricardas Berankis before Evans was edged out in a fluctuating five-set clash with Laurynas Grigelis in Vilnius.
GB must now beat Turkey in a relegation play-off in July to avoid dropping to Europe-Africa Zone Group III.