Bencic leads Switzerland past Italy, Slovakia beat Belgium in BJK Cup
Olympic champion Bencic, the world number 12, saw off Jasmine Paolini (26) 7-5 6-3 to secure the Group A tie for Switzerland after Jil Teichmann (25) saved a match point en route to her thrilling 6-3 4-6 7-6(5) win over Elisabetta Cocciaretto (21).
Bencic returned to court half an hour later to team up with Teichmann and wrap up a flawless day for last year's finalists as they beat Paolini and Martina Trevisan (29) 7-6(5) 6-1 to complete a 3-0 sweep.
Earlier, Viktoria Kuzmova (24) and Anna Karolina Schmiedlova (28) won their singles ties to help secure a 2-1 victory over Belgium in their final Group B tie.
Kuzmova had lost to Ajla Tomljanovic (29) on Wednesday but bagged a valuable doubles point with Tereza Mihalikova (24), and she carried that momentum into her powerful 6-2 7-6(7) win over Ysaline Bonaventure (28) of Belgium.
Schmiedlova sealed the tie for Slovakia in a tenacious 5-7 6-2 6-3 win over Maryna Zanevska (29) before the doubles pairing of Elise Mertens (26) and Kirsten Flipkens (36) got Belgium on the board with a crushing 6-0 6-3 win over Kuzmova and Mihalikova.
The competition, formerly called the Fed Cup, was renamed in honour of the 12-times American Grand Slam champion and restructured into a format concluding with 12 nations competing over one week for the title.
The United States will take on Poland in Group D while Spain face Kazakhstan in Group C later on Wednesday.