Great Britain will face a relegation play-off against Ukraine after losing their Davis Cup Euro-Africa Zone Group One tie to Israel at Eastbourne.
In the end it came down to a few vital points in the middle of the last set which could easily have been mine
The visitors took an unassailable 3-1 lead after Noam Okun beat Jamie Delgado 6-3 6-4 6-7 (5-7) 2-6 6-3.
Delgado, a late replacement for the injured Andy Murray, battled from two sets down to give Great Britain hope.
But Okun overcame an early break in the fifth and final set to claim victory after a run of four successive games.
"I'm bitterly disappointed," said Delgado. "I put everything out there but it wasn't enough in the end.
"I didn't play well at the start but I got myself back in it and when you lose again after all that it's pretty hard to take.
"Being beaten in the doubles in five sets was a big disappointment but when I was asked to take Andy's place today I thought 'let's go for it'.
"I was nervous at the start but I improved as the match went on and I turned it around at one stage.
"But in the end it came down to a few vital points in the middle of the last set which could easily have been mine."
Captain Jeremy Bates added: "I'm enormously proud of what I've seen over the last few days on court.
"In terms of the doubles yesterday, Jamie's singles today and Andy's match on Friday I think that if that is what British tennis is all about we should be enthused by what we can achieve in the future."
Murray, who had played 95 games over the course of Friday and Saturday. pulled out of the first reverse singles with an injured neck and a strained shoulder.
That left Delgado with the task of reviving British fortunes after they had finished the first two days 2-1 down.
The 29-year-old Englishman looked overawed by his sudden elevation as he struggled to break down his opponent in the first two sets.
It was a crazy match and I'm feeling so high
Okun, ranked 270 in the world, played solid tennis and seemed destined for a straight-sets win before Delgado rallied.
Having wasted a glorious chance to win the third set at 5-3 on his serve, Delgado finally gave the partisan Devonshire Park crowd something to cheer when he took the tie-break.
He then raced through the fourth set and broke early in the fifth to give the hosts hope of a tantalising fifth and deciding rubber.
But that dream scenario was shattered as Okun mustered one final push and closed out for a famous win.
"It was a crazy match and I'm feeling so high," he told BBC Sport after sealing the victory. "It was a great, great match.
"I don't know what happened to me in the third and fourth set, I went to sleep a little bit, but my team woke me up.
"I didn't really play bad, but Jamie played out of his mind. At times I didn't know what to do, I had to hang in there and wait to take my chance when he went down a little bit."
Scotland's Alan Mackin beat Israel's Dekel Valtzer 6-2 6-1 in the dead rubber to give close the overall score of the match to 3-2.
Great Britain will play Ukraine in Kiev in late September.