THIS was Andy Murray's longest day. It was widely assumed that he and Juan Martin del Potro were playing at their very limits when they fought out that breathless Olympic gold medal match in Rio de Janeiro five weeks ago but it turned out they were just getting started.

No precious metals were on the line in Glasgow yesterday, just the chance to strike first blood in this Davis Cup semi-final tie, along with copious amounts of national and personal pride. And in the end it was Advantage Argentina as Del Potro exacted revenge for that Rio disappointment, a 6-4, 5-7, 6-7 (5), 6-3, 6-4 win inflicting on the 29-year-old his first ever Davis Cup singles defeat on home soil, let alone in the city of his birth. But if there was a gold medal for guts then the Scot still surely merited one.

Just making himself available for this contest, after all, required a triumph of the will. While the younger Murray brother played his heart out on court, his older brother Jamie quietly departed the scene mid-match, returning to Kilsyth for the funeral of the boys' paternal grandfather Gordon Murray. Regardless of the havoc this mammoth match will have wreaked on the World No 2's body, the two brothers will be paired on a doubles court again today as they try to recover a situation in this tie which is not entirely desperate yet. Realistically, Great Britain captain Leon Smith has no other choice.

Such family turmoil may have been bubbling away somewhere beneath the surface but there was little sign of it on court as these two men went mano-a-mano in the mother of all Davis Cup duels, which lasted 65 minutes longer than their Rio battle and contained even more twists and turns. It was the longest of both player's careers, the Scot outstripping the four hours 54 minutes of his 2012 US Open win against Novak Djokovic and this year's first round Davis Cup victory against Kei Nishikori, and Del Potro going beyond the four hours 34 minutes of his 2013 Wimbledon semi-final against the Serb. If umpire Pascal Maria hadn't called game, set and match Argentina at around half past six you half suspected that the two of them would still be down there this morning, bludgeoning balls at each other just for the sheer hell of it.

Having lost just twice previously in singles rubbers in a decade of play in this competition, to Stan Wawrinka in Switzerland in 2006 and to Fabio Fognini in Naples in 2014, and sailing serenely to 11 Davis Cup wins in Britain's glory year of 2015, the Scot is being made to work significantly harder for his money this time around. After the trauma of Nishikori in Birmingham in January, this was the highest quality match on Scottish soil since Jimmy Connors and John McEnroe met at Craiglockhart in the 1988 Scottish Grass court Championships. Okay so Del Potro, emerging suddenly after a wrist problem, is ranked only No 64 but that is about 60 places too high. His first five set match since early 2014 was another giant leap in his return from wrist problems.

It was a bit much to serve up tennis like this and not expect the people watching it to get a bit carried away from time to time. For all the synergy between the Tartan Army and their Argentinian viewers - epitomised by one man clad in an Argentina football strip and a 'See you, Jimmy' wig - not everything yesterday was sweetness and light. There were at least a couple of episodes of Diego Simeone-style skullduggery by certain members of a sizeable and colourful Argentinian support. One fan situated behind a line judge intervened by calling a good Del Potro serve out, causing Murray to halt in mid flow at a key point, while home fans nearby attempted to point the miscreants out to security. So persistent was the chatter from one area as the Scot's serve was surrendered for the crucial final time that he rebuked them directly. For his part, Del Potro slammed the ball into the ground in disgust and complained bitterly to match referee Stefan Fransson when some premature celebration from British fans marked the Scot levelling matters up at one-set all.

The Del Potro forehand is one of the most fearsome sights in sport. The first warning sign that it is on its way is when the Argentine's right arm points skyward, before its unique, slingy motion propels the ball with a flat trajectory with as much venom as any shot in tennis. With the court at the Emirates Arena particularly fast this week, by the end Murray was earning a standing ovation from the crowd for the shuttle runs he was doing to keep up with it as he vainly attempt to stay in the match. The point duly lost, setting up match point and a Del Potro ace, the shattered Scot simply sat down on the wall and attempted to gather his breath.

It had been a Murray lob which claimed this trophy for the first time in 79 years in Ghent last November and for a while it seemed like the Scot's trademark shot - has there ever been a finer exponent in history? - would do the trick here. He reeled off three beauties before the first two games were out, then produced an even better one when set point down before levelling matters at one set all. The Scot served more aces, 35, than any other match in his career and fate seemed to be smiling on him when he stole the third set in a tie-break. But for once the last man standing wasn't the World No 2. When five hours and 343 brutal rallies were totted up, Del Potro had won three more points than he had.