Novak Djokovic returned to the court just five days after his historic US Open title triumph to lead Serbia into the Davis Cup quarter-finals on Friday, while Andy Murray helped Britain edge past Switzerland.
World number one Djokovic eased to a 6-3, 6-4 success against Alejandro Davidovich Fokina to give his country an unassailable 2-0 lead in Valencia after Laslo Djere's earlier 6-4, 6-4 win over Albert Ramos-Vinolas.
It was Djokovic's first appearance in the team competition since Serbia's semi-final loss to Croatia in 2021.
The 36-year-old won a record-equalling 24th Grand Slam title last weekend with a straight-sets triumph against Daniil Medvedev in the US Open final.
"I'm on cloud nine with everything that has happened recently on the tennis court," Djokovic said.
"Playing for Serbia, for my country, is something completely different.
"It's a huge responsibility and pressure, but it's also a privilege and an honour."
Djokovic took the opening set against world number 25 Davidovich Fokina with a single break in the eighth game, before battling back from 4-1 down in the second set with a run of five straight games.
Serbia have now secured a spot in the knock-out phase which will be played in Malaga in November, after also seeing off South Korea 3-0 on Tuesday, while Spain are out of the competition.
"It can create some pressure," said Djere on having Djokovic back in the team.
"But I try not to put any pressure on myself and use it as motivation. I think I managed quite good in doing so."
Djokovic played a starring role when Serbia won their only previous Davis Cup title in 2010.
Serbia wrapped up a 3-0 victory in the Group C tie as Nikola Cacic and Miomir Kecmanovic beat Davidovich Fokina and Marcel Granollers 6-4, 7-6 (15/13).
They will round off their group campaign against the Czech Republic on Saturday.
- Britain post second win -
An emotional Murray won the opening rubber of Britain's victory over Switzerland before revealing he had missed his grandmother's funeral to play.
"Today is a tough day for me, it's my Gran's funeral today," Murray said after his epic 6-7 (7/9), 6-4, 6-4, win over Leandro Riedi at the Manchester Arena.
"I'm sorry to my family that I'm not able to be there but Gran, this one's for you."
The 36-year-old had only lost three of his previous 35 singles matches in the competition but needed every ounce of skill and competitiveness to see his way past 21-year-old Riedi, who was making his Davis Cup debut.
The Swiss levelled the tie as veteran Stan Wawrinka quietened the crowd with a 7-5, 6-4 win against Cameron Norrie.
But Dan Evans and Neal Skupski brushed aside Dominic Stricker and Wawrinka 6-3, 6-3 as Britain made it two wins from two in Group B after also beating Australia earlier in the week.
Britain can secure a last-eight berth if they beat France on Sunday, while even a loss could be enough depending on the result of Saturday's tie between Switzerland and Australia.
Italy bounced back from their surprise opening defeat by depleted reigning champions Canada in Group A, downing Chile 3-0.
Youngster Matteo Arnaldi battled past Cristian Garin 2-6, 6-4, 6-3 before Lorenzo Sonego edged out Nicolas Jarry 3-6, 7-5, 6-4.
Sonego then teamed up with Lorenzo Musetti for a 6-7 (3/7), 6-3, 7-6 (7/2) doubles victory against Tomas Barrios Vera and Alejandro Tabilo.
Finland kept their hopes of progressing alive with a 2-1 win over Croatia in their Group D clash in Split.