Canada completed a team-tennis double on Sunday as their women took the Billie Jean King Cup for the first time, winning both singles rubbers to build an unassailable lead over Italy.
Canada's men are the reigning Davis Cup champions after winning their first title in Malaga last November.
Marina Stakusic, an 18-year-old, opened the final in Seville with a 7-5 6-3 victory over Martina Trevisan, capping a stunning week for the rookie.
"We took a risk by selecting a young player, and it paid off," said Canada's coach Nathalie Tauziat.
Leylah Fernandez then beat Jasmine Paolini 6-2, 6-3, to spark jubilation from the Canadian team.
"I'm extremely happy, ecstatic," said Fernandez.
Canada, captained by Heidi El Tabakh, became the 13th nation to win the Billie Jean King Cup and the second consecutive new champion after Switzerland won in Glasgow 12 months ago.
Stakusic, ranked 258th in the world, beat three top 100 players this week, including Trevisan.
Fernandez defeated Czech Wimbledon champion Marketa Vondrousova in the singles semifinals rubber on Saturday before playing again in the decisive doubles, as she too shone in the south of Spain.
"Leylah played her role as leader and that made all the difference," said Tauziat. "She prepares like a boxer, ready to enter the ring, to receive blows and to give them."
Fernandez said the victory had taken time.
"You know, it's the first time that Canada has ever won the Billie Jean King Cup. I can finally say this – we're world champions, and we rightfully deserve it," she said.
"We worked really hard the past years, and, you know, I think every year, as I said before, we just keep improving."
"It's showing on the tennis court. It's showing in competition, individual competitions. Now it has shown on the biggest stage in the world."
Italy continued their 10-year drought in the competition, known as the Fed Cup until 2020, having won the last of their four titles in 2013.
"It's been a very tough week for me, mentally and of course physically," said Trevisan.
"We spent a lot of energy on court and of course out of the court. Maybe today my physical energy was, well, a little bit low.
"I'm a player that need to be very fast on court, and today I wasn't too much – it wasn't enough."