Michael Chang and Todd Martin swept straight-set victories Friday to give the heavily favored United States team a commanding lead over Mexico in the first round of the Davis Cup.

Chang downed Leonardo Lavalle 6-1, 6-2, 6-4, and Martin beat Alejandro Hernandez 6-3, 6-3, 6-0 to put the defending Davis Cup champions up 2-0.

Patrick McEnroe and Patrick Galbraith can lock up a U.S. victory with a doubles win over Mexico’s Luis Herrera and Oscar Ortiz today. Two more singles matches, rendered meaningless if the U.S. doubles team wins, are scheduled for Sunday.