Canada opened their title defence by downing Italy as Great Britain upset Australia on the second day of Davis Cup final group stage action on Wednesday.
The Czech Republic won their tie against a Spain side sorely missing world number two Carlos Alcaraz, while US Open men's doubles champion Rajeev Ram helped the United States team battle past Croatia.
The top two from each of the 16-team four group round robin will move into the knockout phase in Spain in November.
Canada stayed on course for the grand finale in Malaga next month courtesy of straight set wins in the opening singles by Alexis Galarneau and then Gabriel Diallo.
Galarneau and Vasek Pospisil then claimed a tense 6-7 (4/7), 6-4, 7-6 (7/3) win over Matteo Arnaldi and Simone Bolelli to defeat the Italians 3-0 in Bologna.
Canada are trying to become the first nation in a decade to win the tournament back-to-back.
The last country to achieve the feat, the Czech Republic in 2012-2013, exploited the absence of Alcaraz in Valencia to beat Spain 3-0 and join Serbia at the top of Group C.
Over in Manchester the Great Britain captain Leon Smith's gamble in opting to select Jack Draper and Dan Evans in preference to his highest-ranked team member Cameron Norrie or experienced veteran Andy Murray as his singles players paid off handsomely.
Davis Cup debutant Draper, who made it through to the US Open fourth round, repaid Smith's faith in him with a 6-7 (6/8), 6-3, 7-6 (7/4) win over Thanasi Kokkinakis.
In front of a 9,000 crowd Draper broke Kokkinakis when his Australian rival was serving for the match, and then fired a final backhand winner down the line to clinch the deciding tie break after almost three hours play to get the hosts off to a dream start.
Evans then got the better of world number 12 Alex de Minaur 6-1, 2-6, 6-4 to sink last year's finalists.
Last year's runners-up Australia took the doubles to leave the home side 2-1 winners, with the 2015 champions second to France, who beat Switzerland 24 hours earlier, in Group B.
Draper was buzzing from his first taste of Davis Cup competition.
"There's nothing better. It was a real battle, massive crowd in here," he said on court.
- Tiafoe toppled -
"It's amazing to play my first Davis Cup tie in the UK in this sort of arena. I'm just so happy to be here and grateful Leon trusted me and put me out here today."
He added: "I knew I'd played some tough matches at the US Open and I felt really good about my tennis. That helped the nerves a lot.
"When I got out there with the home crowd and all those people supporting me, it felt amazing. I haven't played too many great matches this season but I think that was one of them."
The United States had to dig deep in Split to overcome hosts Croatia 2-1.
Mackenzie McDonald got the record 32-time winners off to a positive start with a 6-4, 6-2 win over 18-year-old Dino Prizmic.
Borna Gojo then levelled the tie by toppling US Open quarter-finalist Frances Tiafoe (USA) 6-4, 7-6 (8/6).
That left everything resting on the fate of the closing doubles, with Ram, fresh from his third straight title at Flushing Meadows, linking up with Austin Krajicek to see off Ivan Dodig and Mate Pavic 7-6 (7/5), 6-7 (3/7), 6-2.
On Thursday Canada face Sweden, the Czech Republic take on South Korea, France play Australia and the USA come up against the Netherlands.