World number three Federer got defending champions Switzerland off to a good start at the RAC Arena, defeating Britain's Cameron Norrie 6-1, 6-1.

Bencic then beat Norrie's compatriot Katie Boulter 6-2, 7-6 to put the tie beyond doubt. 

Federer and Bencic ensured a clean sweep against their opponents when they won the doubles match 4-3, 4-1.

There was another straight win in Group A, with Germany comfortably defeating Spain 3-0.

World number two Angelique Kerber beat Garbine Muguruza 6-2, 3-6, 6-3 before Alexander Zverev triumphed against David Ferrer 6-4, 4-6, 7-6.

The duo then won the doubles match 4-3, 4-1.

Tomorrow is due to see a morning match of the United States against Greece in Group B.

Elsewhere in Australia, the qualifying rounds of the Brisbane International were taking place at the Pat Rafter Arena.

Destanee Aiava of Australia defeated Christina McHale of the United States 7-5, 6-1 to set up a round of 32 tie with Kristina Mladenovic of France.

Britain's Harriet Dart won against Andrea Petkovic of Germany 7-5, 6-2 to set-up a meeting with Australia's Priscilla Hon in the next round, while Marie Bouzková of the Czech Republic beat Swiss Viktorija Golubic 4-6, 6-1, 6-2 to play Australian Samantha Stosur.

It also took Anastasia Potapova of Russia three sets to defeat her opponent, Czech Karolína Muchová, 1-6, 7-6, 6-0.

She is now set to face Aliaksandra Sasnovich of Belarus in the round of 32.

The competition proper of the Women's Tennis Association Premier event is due to start tomorrow, with matches including Belgium's Elise Mertens against Kiki Bertens of The Netherlands and Sloane Stephens of the US against Britain's Johanna Konta.

Japan's US Open champion Naomi Osaka and Ukraine's Elina Svitolina have received byes into the round of 16.