Great Britain were unable to clinch a rapid Davis Cup victory over the United States on Saturday as defeat in the doubles kept the match alive.
The British pair of Colin Fleming and Dominic Inglot, playing in place of the rested Andy Murray, were no match for Bob and Mike Bryan, who clinched a 6-2 6-3 3-6 6-1 victory in San Diego.
It left Britain leading the World Group first-round tie 2-1 following singles victories for Murray and James Ward on day one.
Murray can seal their place in the quarter-finals by beating Sam Querrey in the opening match on Sunday.
Captain Leon Smith opted to give the Wimbledon champion the day off on Saturday with that match in mind, deciding to keep him as fresh as possible, given his run to the Australian Open quarter-finals and the fact he is still feeling his way back into the rigours of the main tour after back surgery.
A win on Sunday, should the Scot pull it off, would seal Britain's first win over the US since 1935.
The Bryan brothers, doubles specialists, knew only a win would do on the newly-laid clay at Petco Park, home of the San Diego Padres baseball team, and they got off to a flying start as two breaks of serve handed them the first set.
Fleming and Inglot are decent doubles players - the latter reached the quarter-finals of the Australian Open last month and of last year's US Open - but they struggled to trouble their opponents, who broke for a 5-3 lead in the second set before seeing it out.
With Murray offering encouragement from courtside, the British duo fought back, breaking for a 4-2 lead in the third before clinching it 6-3.
They made the worst possible start to the fourth, though, as the US broke for a 2-0 lead and then again to go 5-1 in front.
And the Bryans duly closed out the match to take the tie into a third day.
It left Britain needing one more win on Sunday, either from Murray's meeting with Querrey or Ward's clash with Donald Young, to move into the quarter-finals.
Mike Bryan told BBC3 afterwards: "I thought we played a great match against two top players.
"I think it was Inglot's first Davis Cup match and he brought it. They started playing great in the third set.
"I'm really happy to win this and give our team a chance."
Looking ahead to Murray's clash with Querrey, he said: "Andy is the heavy favourite, but Sam can beat anyone. He has one of the biggest serves in the world. He is going to play with less pressure than yesterday (when he lost in five sets to Ward), Andy might be a little off."
Bob Bryan added: "Andy is a grand slam champ, but Sam has beaten him before."