Daniil Medvedev powered the Russian Tennis Federation to an unassailable 2-0 lead over Ecuador in the Davis Cup Finals with a 57-minute thrashing of Emilio Gomez in Madrid.

Gomez did not win a game until 3-0 down in the second set, an achievement met with loud cheers from the crowd.

Russia's Andrey Rublev earlier overcame a second-set wobble to beat Robert Quiroz 6-3 4-6 6-1.

Rublev will partner Aslan Karatsev in the doubles against Gonzalo Escobar and Diego Hidalgo.

Medvedev dropped just 13 points on serve and only made six unforced errors as he outclassed Gomez.

"What is good about Davis Cup is that every match counts," said Medvedev, competing under the Russian Tennis Federation banner because of the global ban on Russia at major sporting events.

"Hopefully the guys will make the doubles fast and then we can prepare for tomorrow's match [against Spain]."

World number one Novak Djokovic beat Jan-Lennard Struff to level Serbia's Group F tie with Germany at 1-1.

Djokovic beat Struff 6-2 6-4 after Filip Krajinovic lost 7-6 (7-4) 6-4 to Dominik Koepfer in the first rubber.

There were wins for Kazakhstan and Australia on the third day, after Great Britain beat France 2-1 earlier on Saturday.

Kazakhstan fought back from losing the first rubber to beat Sweden 2-1 in their Group B tie.

Elias Ymer began the tie strongly with a 6-4 7-6 (7-4) victory over Kazakh stalwart Mikhail Kukushkin in Madrid.

However, Alexander Bublik beat Ymer's younger brother Mikael 3-6 6-4 6-0, before Andrey Golubev and Aleksandr Nedovyesov beat Andre Goransson and veteran Robert Lindstedt 6-3 6-3.

Alex de Minaur came through a gruelling singles rubber to put help Australia recover to a 2-1 win over Hungary.

Australia, 28-time champions at the Davis Cup, lost their opener to Croatia and started poorly in Turin.

John Millman suffered a surprising 4-6 6-4 6-3 to world number 282 Zsombor Piros, but Australia were given hope as De Minaur gritted his way past Hungarian number one Marton Fucsovics 7-5 2-6 7-6 (7-2).

Alex Bolt and John Peers clinched the decisive doubles rubber 6-3 6-7 (11-13) 6-3 over Piros and Fabian Marozsan in a match that lasted just over two hours.

The Davis Cup Finals are being held across three cities, with the semi-finals and final being held in Madrid from 3 to 5 December.

Teams play two round-robin ties, each featuring two singles and one doubles rubber all played over best-of-three sets.

The top teams from each group and the two best runners-up qualify for the quarter-finals.