World number one Rafael Nadal brushed aside Uruguay's Pablo Cuevas to seal Spain's second straight win in the round-robin stage of the inaugural ATP Cup in Perth.
Nadal's 6-2 6-1 win gave his team an unassailable lead in the tie before Pablo Carreno Busta and Feliciano Lopez beat Ariel Behar and Juan Martin Fumeaux 6-1 3-6 10-3 to complete a 3-0 victory.
Spain's win puts them in a strong position to qualify for the final stages of the competition as they prepare for their final round-robin match against Japan on Thursday.
Nadal told atptour.com: "It was a positive victory. I played a very solid match and my serve worked better than the first day. (But) it (Thursday) is going to be a tough one."
In Brisbane, Novak Djokovic beat Gael Monfils to give Serbia a strong start against France before returning to the court to play a crucial role in the decisive doubles match.
Djokovic's 6-3 6-2 triumph over Monfils was cancelled out by Benoit Paire's 6-2 6-7 (6) 6-4 win over Dusan Lajovic, taking the Group A showdown down to the wire.
But Djokovic showed no ill effects when he joined Viktor Troicki to beat doubles specialists Nicolas Mahut and Edouard Roger-Vasselin via a final set tie-break 6-3 6-7(5) 10-3 and claim victory.
Wins for Dominic Thiem and Dennis Novak over Diego Schwartzmann and Guido Pella respectively helped Austria ease to a 3-0 win over Argentina in Group E.
Marin Cilic beat Kacper Zuk 7-6 (8) 6-4 as Croatia beat Poland 2-1, while there were also wins for South Africa and Japan.
Elsewhere, Jeremy Chardy set up a meeting with top seed Stan Wawrinka in the second round of the Qatar Open.
Chardy needed three sets to get past fellow Frenchman Gregoire Barrere 6-3 3-6 6-3.
Adrian Mannarino, also of France, beat Kazakhstan's Alexander Bublik 6-3 6-4 and Fernando Verdasco won the all-Spanish showdown against Pablo Andujar 6-4 6-3.
Sixth seed Filip Krajinovic beat Britain's Kyle Edmund 4-6 6-3 6-3 and fellow Serbian Miomir Kecmanovic swept past Australian Jordan Thompson 6-4 6-2.