Britain moved to the brink of earning a quarterfinal berth thanks to a comeback win by Ward over Sam Querrey.
The United States' doubles team of Bob and Mike Bryan must come through with a win on Saturday to keep the Americans alive.
Querrey then got off to a quick start in the day's second match, but Ward eventually prevailed 1-6, 7-6 (7-3), 3-6, 6-4, 6-1. The match lasted more than 3 hours.
The Bryans will meet the British team of Murray and Colin Fleming Saturday. Sunday's scheduled singles matches in the best-of-five competition will send Murray against Querrey and Young against Ward.
The matches are being played on a clay court in the home stadium of the San Diego Padres. It is the first time the Americans have chosen to play a home Davis Cup series on clay in 22 years.
Britain was one of five nations to take a 2-0 lead on the opening day of the 2014 Davis Cup. Those with 2-0 leads included Germany over Spain, France over Australia, Kazakhstan over Belgium, and Switzerland over Serbia.
There was a 1-1 tie in the other three series -- the Czech Republic vs. Netherlands, Japan vs. Canada and Argentina vs. Italy.
The winner of the U.S.-Britain matches will meet the Argentina-Italy survivor in April.