Roger Federer and Stanislas Wawrinka enjoyed opening-day victories to give Switzerland a 2-0 lead against Serbia in their Davis Cup World Group match.
Federer eased to a 6-4 7-5 6-2 win over Ilija Bozoljac before Australian Open champion Wawrinka battled past Dusan Lajovic 6-4 4-6 6-1 7-6 (9-7).
Jo-Wilfried Tsonga and Richard Gasquet both won to give France a 2-0 lead over Australia in another first-round tie.
Defending champions the Czech Republic are tied 1-1 with the Netherlands.
Kazakhstan lead Belgium 2-0, while Japan and Canada are tied at 1-1.
Frenchman Tsonga saw off a gutsy effort from Australian veteran Lleyton Hewitt, prevailing 6-3 6-2 7-6 after Gasquet outclassed Nick Kyrgios 7-6 6-2 6-2.
Dutch number one Robin Haase beat Radek Stepanek in five sets - 3-6 6-4 6-7 6-2 6-1 - to give the Netherlands the lead over the Czechs.
World number seven Tomas Berdych then brought the hosts level after beating Igor Sijsling 6-3 6-3 6-0.
Great Britain lead the United States 2-0 in their first-round match.
The matches are all the best of five.