A stunning comeback from James Ward put Great Britain 2-0 up against the United States following a marathon first day of Davis Cup action in Glasgow.
Ward was two sets down against John Isner but was always close to the American No 1 and he dug out a sensational fightback to win 6-7 (4/7) 5-7 6-3 7-6 (7/3) 15-13.
Isner saved five match points but Ward finally prevailed after the world No 20 hit a backhand into the net from close range.
Andy Murray had earlier thrilled his home crowd with a lightning start to the World Group first-round encounter, taking the first two sets inside 46 minutes against Donald Young.
Young fought back admirably after looking out of his depth but Murray ultimately cruised home 6-1 6-1 4-6 6-2.
Murray admitted he had been charged up by the atmosphere in front of more than 7,500 fans.
“When you play in an indoor arena everything feels so much louder and the noise stays in,” he said.
“It was very nice and I used that energy and emotion very well at the beginning of the match. I played extremely well, I would say for the whole match. I maybe had a slight lull in intensity but I couldn’t maintain the intensity I had in the first couple of sets for the whole match.”
Asked if he thought Young had been intimidated by the atmosphere, Murray said: “He didn’t start the match well but I made one unforced error in the first two sets.
“So, I can’t say it was down to his bad play why I was in that position.”
Ward and Isner were evenly matched throughout and the Briton had been 4-2 up in the first-set tie-break, but his opponent got a stroke of fortune with a net shot and never looked back.
The American edged further ahead after finally breaking in the 11th game of the second set when Ward was wide with a backhand, finishing the set off with a trademark power serve.
The third set started in a similar fashion with serves being held but Ward brought the house down with two cross-court shots to break in the sixth game, before going on to seal the set with an ace.
The pair remained neck and neck throughout the fourth set but Ward, who is ranked 111 in the world, quickly took control of the tie-break and won 7-3.
Isner prevailed 70-68 final-set triumph against Nicolas Mahut at Wimbledon in 2010, a match that lasted 11 hours and five minutes, and he looked like hanging on in Glasgow but Ward showed no sign of wilting and eventually prevailed to the delight of a vocal home crowd.