GLASGOW -- No one -- not even the surging, soaring, free-swinging Juan Martin del Potro -- beats Andy Murray twice in Scotland within 24 hours.
Del Potro has accomplished much during his comeback year, but establishing absolute primacy in the city of Murray's birth was beyond him.
Just a day after his gargantuan singles victory over Murray at this Davis Cup semifinal -- which the Argentine had taken in five sets and five hours, in the longest match each of them had ever played -- they came together again for the doubles rubber.
Del Potro's victory Friday had been spoken of as his 'revenge' after last month's Olympic singles final, which had gone the other way, and this time, with his brother Jamie alongside him, it was Murray's turn to be the avenger with a victory that kept Britain, who had trailed 0-2 overnight, in the tie.
By comparison with their singles match, this was quite brief, with the Murrays defeating Del Potro and Leonardo Mayer 6-1, 3-6, 6-4, 6-4 inside three hours to maintain their record of never having lost a Davis Cup rubber together. "We're back in the tie," said Jamie, with this doubles match coming just a day after the funeral of their paternal grandfather, Gordon Murray.
Only twice before have Britain come from 0-2 to win a tie -- against Germany in 1930 and against Russia in 2013. But this is a team that has already accomplished the supposedly impossible by winning the entire competition last season, the nation's first triumph since 1936.
Murray will be expected to win the first of Sunday's reverse singles rubbers, when he is scheduled to face Guido Pella, so this tie will probably be decided in the fifth rubber when either Dan Evans or Kyle Edmund will encounter Del Potro.
Hadn't Del Potro spoken Friday evening of having "cramps everywhere"? So there was much astonishment when -- an hour before the doubles rubbers began -- Argentina disclosed they had tinkered with the original nominations they had put forward at Thursday's draw ceremony, with Del Potro to feature instead of Federico Delbonis.
At first glance, this appeared to be a very big call by the Argentine captain, Daniel Orsanic -- bold bordering on eccentric -- but in all probability it wouldn't have been his decision, but Del Potro's. Once Del Potro had decided he wanted to play doubles, who on earth was going to block him from taking to this indoor hard court?
But wouldn't it have made more sense for Del Potro to have rested on Saturday in readiness for Sunday? True, Andy Murray was also fatigued after Friday's exertions -- and there had been some doubt about whether he would participate -- but there was a logic to the Wimbledon and Olympic champion playing doubles. Quite simply, it was a rubber that Britain had to win to stay in the tie.
Watching the Murray brothers together on the doubles court, there's some doubt as to which of them should be considered the senior player. While Andy is undeniably the more talented, and certainly the more celebrated after his accomplishments in singles, this is the form of the game which Jamie specialises in.
There are few better than Jamie at playing doubles -- earlier this year he became the first British man to hold the world No. 1 ranking, whether in singles or doubles, though he has since lost that status and is currently fourth.
Jamie's new elite status has come through his partnership with Brazilian Bruno Soares, which was new this year -- they had immediate success at the Australian Open, where Jamie won his first men's doubles Grand Slam title. Just over a week ago, Jamie and Soares scored another major at the US Open. Perhaps neither of the Murrays is the senior player, with the doubles court the only place where they are truly equals.
After Andy and Del Potro's long-running singles match, the opening set of this doubles match was remarkably brief, lasting a mere 26 minutes. But anyone with any previous exposure to Britain's Davis Cup ties must have realised this couldn't possibly continue in such a one-sided, straightforward manner, and the South Americans took the second set and were well-placed to snaffle the third, too, after breaking for a 4-3 lead.
But the Murray brothers raised their level, breaking once for parity and then once more for the set. The fourth set was theirs, too.