Britain celebrated their first Davis Cup tennis victory over the United States since 1935 when Andy Murray beat Sam Querrey 7-6 6-7 6-1 6-3 in the World Group first-round tie in San Diego.
Wimbledon champion Murray broke his big-serving opponent five times to give Britain an unassailable 3-1 lead with James Ward scheduled to take on American Donald Young in the final match.
Murray sealed victory over the 49th-ranked Querrey in just under three hours.
Ward, the world number 175, had given Britain a commanding 2-nil advantage over the Americans on day one with a shock win over Querrey after clawing his way back from two sets to one down and trailing 2-4 in the fourth.
Britain will travel to Italy in the quarter-finals.
