British pair Colin Fleming and Ross Hutchins wrapped up victory over Hungary with a day to spare in Glasgow.
After wins for James Ward and Andy Murray at Braehead Arena on Friday, Fleming and Hutchins were expected to finish the job, and they did just that, beating Attila Balazs and Kornel Bardoczky 6-3 6-4 6-4 to give the hosts an unassailable 3-0 lead.
Despite injury problems, Fleming and Hutchins have had an impressive season, reaching the quarter-finals at Wimbledon and the US Open, and this was a chance to prove they can be a reliable doubles pair for Britain at a higher level.
Balasz looked a much better player than he had during his singles defeat by Ward on Friday while Bardoczky was also capable of hitting some searing winners, but overall the British pair always appeared to have the edge.
There were some shaky moments in the first set, particularly on the Fleming serve, but the Scot held on and the crucial break was secured in the eighth game.
Hutchins had lost all four of his previous Davis Cup matches, including a rubber with Fleming against Ukraine two years ago, but both players have improved significantly since then while Saturday's opposition did not provide the biggest challenge.
Britain began the second set by winning eight straight points but the Hungarians stayed in contention and it was not until the fifth game of the third set that Fleming and Hutchins broke again, celebrating with a Bryan brothers-style chest bump.
And that proved enough for the pair to secure victory, Fleming holding his serve with ease in the final game to give Leon Smith's side a fourth straight win as Hungary went the same way as Turkey, Tunisia and Luxembourg.
Smith's side will return to the second tier of the competition next year for the first time since 2009, where much tougher challenges will await.