Andy Murray secured Britain's return to the Davis Cup World Group after a five-year absence when he defeated Croatia's Ivan Dodig 6-4, 6-2, 6-4 in a playoff rubber at Umag on Sunday.
That made the match score 3-1 in Britain's favour with just the second of the reverse singles to follow.
Wimbledon and Olympic champion Murray won his opening singles on Friday and teamed up with Colin Fleming to win the doubles on Saturday.
Dodig, who beat Dan Evans in straight sets on Friday, put up some resistance early on but tired badly in the second set and Murray coasted away to clinch the win that puts Britain back among the elite of world tennis.
"I thought it was pretty good match. I didn't give him a lot of opportunities on my serve," said the world number three.
"I had to come out and serve for it and it was tough. The atmosphere was pretty hostile at the end and you dont get that in Grand Slam matches. It's a character builder.
"I was nervous today and it was a big match for us to get back into the World Group.
"But I've dealt with enough pressure at Wimbledon time to know how to conquer the fears you have when you come on to the court.
"I am looking forward to it - to play some of the biggest countries in the world so it's exciting for all of the guys."
For Croatia, the defeat means that they fall out of the World Group for the first time since 2008, having won the trophy in 2005.
"It was an extremely difficult match for me," said Dodig, who was taking the lead role in the team due to the absence of Marin Cilic.
"I tried all I could, but on the other hand Murray was an excellent opponent against whom I should have to play well above my abilities to win."