ANDY Murray woke on the morning of September 18, 2014, and tweeted his support of Scottish independence. Yesterday, precisely two years on from referendum day, he put his body on the line for Great Britain. Again, there was only so much he could do to influence the result.

Juan Martin del Potro might have dented the Scot's status as the strong man of this squad in just over five hours of play on Friday, but when it comes to pushing yourself through the pain barrier it turned out there was no competition.

The giant Argentinian - perhaps understandably considering his three years spent nursing an injured wrist - laid down the law to his captain Daniel Orsanic about his participation in the final rubber, cursing his sore "legs, shoulders, wrist and back" after eight hours of play this weekend. But the Scot signalled he was ready to strain every sinew to retain this trophy.

Read more: Murray shows us where his limits are after opting not to reveal all​The Herald: Andy Murray refused to take credit for compatriots' success. Picture: Getty

The 29-year-old, who has only retired hurt twice in a career spanning more than a decade, is the kind of man who has to be carried out of battle. Unfortunately, yesterday that was nearly the case.

He seized up during that third set after experiencing a sharp pain in his right quad, a wound sufficiently grievous for him to leave court for a 10-minute medical time-out to get massage and strapping on the affected area. Panic spread like wildfire around this arena as the Glasgow crowd wondered whether that was that.

Read more: Superior man-power gives Argentina captain the upper hand

The thought didn't even enter the Scot's mind. Instead, he merely wondered how much further damage he would sustain before he got over the line. Returning to a hero's welcome, Murray held serve, then broke the Pella delivery before seeing out the remainder of this match. But every rally was a form of torture, the World No 2 hirpling from shot to shot, effectively forced to defeat his opponent with one leg.

Del Potro might have made the 'smart' choice, but it wasn't just the Argentine who had to weigh up his desire to be involved in this event with the promise of future events down the line. The Scot is in the midst of his best-ever year and still has Asian hard court events in Beijing and Shanghai to negotiate as he builds up to the ATP World Tour finals. It would be galling if his exertions cost him the chance to overhaul Novak Djokovic and become World No 1 for the first time.

Yet so much did he put himself through the ringer in this team event that one suspected might be the first man in history to be forced to withdraw from playing action in his own exhibition event, the Andy Murray Live show at the SSE Hydro on Wednesday night. While he admitted afterwards that the timing wasn't exactly "ideal", the Glasgow public for the charity event will hardly expect him to be performing cartwheels.

At that point, of course, it was anyone's guess who would be turning up to contest the final rubber, let alone who would win it. Eagle-eyed observers spent as much time watching who the players come and go from the benches courtside as they searched for clues.

Enough newsprint by now has been devoted to how this fiercely patriotic 29-year-old Scot sees no contradiction with racking up points for Great Britain. Whether Scotland gets enough support from the LTA in return for the efforts of he and his brother is a different question but the chances of Leon Smith's side reaching their second successive Davis Cup final looked grim when their Argentine visitors racked up a 2-0 first day advantage. By the time the World No 2 walked off court here everything was up for grabs again.

For all the flag-waving which surrounded him yesterday, this was the most single-minded of rescue missions. At one point, via captain Leon Smith, the umpire passed on the instruction 'Lady, could you please put the flag down during the rally'. The flag in question happened to be a saltire, even if it the bearer wasn't first minister Nicola Sturgeon, situated a few rows away.

As narrow as the margins were when he went down to Del Potro in five gruelling hours on Friday, surrendering his perfect singles record on home soil was something the World No 2 took personally. Pella, an impressive conqueror of Kyle Edmund on the opening day, simply bore the brunt of it.

The 25-year-old from Buenos Aires has worked his way quietly into the world's top 50 for the first time this year but Murray preached pre-match about the virtues of playing the points on his terms and was true to his word. So stealthily did he sneak into the net to cut lengthy rallies short and despatch volleys away that you had to remind yourself that this was the same man upbraided earlier in his career for his reluctance to leave the baseline. It wasn't until the third set, when the cumulative effect of it all took its toll, that the Scot experienced any discomfort.