Novak Djokovic eased to a 6-3, 6-4 win against Alejandro Davidovich Fokina to send Serbia to the Davis Cup quarterfinals in Group C on Friday. Meanwhile, Andy Murray helped Britain edge past Switzerland. 

Djokovic, who made his first appearance after a historic U.S. Open title triumph over Russian Daniil Medvedev, gave his country a 2-0 lead against Spain after Laslo Djere's opening win over Albert Ramos-Vinolas.

"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 honor," he added.

Djokovic took the opening set with a single break in the eighth game, before battling back from 4-1 down in the second with a run of five straight games.

Team Serbia, which has won the event once in 2010, later wrapped up a 3-0 victory as Nikola Cacic and Miomir Kecmanovic beat Davidovich Fokina and Marcel Granollers 6-4, 7-6 (15/13).

In Group B, 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 Davis Cup debutante Leandro Riedi.

"I'm sorry to my family that I'm not able to be there but gran, this one's for you."

The Swiss team levelled the tie as veteran Stan Wawrinka won 7-5, 6-4 against Cameron Norrie, before Dan Evans and Neal Skupski brushed aside Dominic Stricker and Wawrinka 6-3, 6-3. Britain will continue their hunt for a berth in the last eight, after seeing off Australia 2-1 two days ago, as they round off their group stage campaign on Sunday against France. 

Elsewhere, Italy downed Chile 3-0 to bounce back from an opening defeat to reigning champions Canada in Group A, and Finland kept their hopes of progressing alive with a 2-1 win over Croatia in Group D.

(With input from AFP)