Murray battled to a 6-7 (7) 6-4 6-4 victory over debutant Leandro Riedi in three hours and 10 minutes at Manchester’s AO Arena before breaking down in tears during his on-court interview.
“Today is a tough day for me, it’s my gran’s funeral today,” he said. “I’m sorry to my family that I’m not able to be there but gran, this one’s for you.”
Murray then returned to his bench where he sat sobbing into his towel.
Asked in his press conference later whether he had considered not playing, the Scot said: “I spoke to my dad about it and he said that she’d want you to play. He just said make sure you win, so I did.”
Murray had not even told captain Leon Smith, who said later: “That would have been very difficult for him. I really feel for him. It just shows his strength of character to do what he did today.
“I’m sure that was tough for him to miss. All you can say is what he then goes out and does is really quite incredible, and it was vitally important as well.”
The circumstances of Murrray’s victory made his efforts in coming through another long and tense battle even more impressive.
The 36-year-old had only lost three of his previous 35 singles matches in the competition and never to a player ranked as low as world number 152 Riedi, but the big-hitting 21-year-old produced a performance well above that.
Having seen his gamble to play debutant Jack Draper and Evans handsomely pay off in Wednesday’s victory over Australia, Smith made use of his options by naming Murray and Norrie as his singles players here.
Initially it looked like it might be a comfortable afternoon for Murray who, after negotiating an 11-minute first game, had a chance to open up a 4-0 lead.
He could not take it, though, and Riedi worked his way into the contest, beginning to cause Murray increasing problems with his big forehand and aggressive tactics.
They earned him a break back when the Scot served for the set at 5-3, and Murray was then unable to take two set points in the tie-break, Riedi converting his first opportunity with his 22nd winner.
The young Swiss, who had never previously beaten a top-50 player, had his tail up and Murray kicked his bag in frustration after failing to break in the third game of the second set.
He finally made the breakthrough at 3-3 only for Riedi to play a blistering return game. Undeterred, Murray engineered another break and this time held onto it with trademark grim determination to level the match.
Ultimately experience won, although it was still nip and tuck, with Murray slamming his racket to the court after handing an early break back in the decider. He broke again to lead 3-2, though, and quashed Riedi’s hopes of a comeback by taking his first match point with an ace.
Murray said: “It’s obviously incredible to get through that one, it easily could have gone the other way.
“It was ridiculous the shots he was pulling off, amazing, amazing returning. I kept fighting and tried to stay focused and managed to turn it round.”
Norrie was unable to match Murray’s efforts, though, his struggles continuing, leaving Evans and Skupski to try to finish the job.
They have established themselves as Smith’s preferred doubles pair and produced a fine performance against Wawrinka and Stricker to put Britain top of the group table ahead of Sunday’s clash with France.
They will qualify on Saturday if Switzerland beat Australia but victory for Lleyton Hewitt’s side would leave them with work still to do.