With a final place against either Croatia or France in November at stake, Pella’s win leaves Argentina needing just one more victory from either Saturday’s doubles or the two remaining singles on Sunday to eliminate the holders and secure a fourth final spot in the past 10 years.

“I am very happy to get the second point for Argentina and the team,” Pella said.

“Juan Martin played an amazing match and I knew this was my chance.”

Edmund, though, couldn’t hide his disappointment after the match.

“It is tough to reflect on it right now,” said the 21-year-old said, who stepped up in Murray’s absence to claim two singles victories in the quarter-final defeat of Serbia in July.

Watch: Guido Pella v Kyle Edmund highlights

“I know where I went wrong. I felt fine out there and felt I was hitting the ball right but there were errors at key moments and need to get the balance a lot better to win.”

World number ones Great Britain haven’t defeated Argentina since 1928 and their hopes of ending that run took a blow before Edmund took to the court following Del Potro’s defeat of home crowd favourite Murray.

Earlier, Del Potro had helped Argentina get off to a flying start with a 6-4, 5-7, 6-7 (5-7), 6-3, 6-4 victory over Murray in an epic encounter that, at five hours and seven minutes, was the longest match of both players’ careers.

“It was an important victory for us. I feel so tired. I’ve got cramps everywhere,” a delighted Del Potro said.

“I think we both played at a very high level for five hours. The crowd enjoyed that and when you win these kind of matches it is great.

“I still remember the Olympics, but this is important for me and the team and we are looking forward to reaching another final in the Davis Cup.”

Watch: Juan Martin Del Potro v Andy Murray highlights

It was Murray’s first home defeat in the competition and he thought there had been nothing to separate the pair in the rubber.

“It was very fine margins. That happens in tennis and sport sometimes when it could go either way and there wasn’t much difference in the match,” Murray said.

“I thought I did great today. I fought for every point and tried the best that I could and that’s all that you can do.”

Murray will have little time to recover and is expected to partner big brother Jamie in the doubles on Saturday, but won’t make a decision until the morning.

“I don’t know how I will recover. I’ve never played a match that long. I’ll have to see how I pull up tomorrow when I wake up and probably make a decision then,” the Scot said.