Great Britain trail 2-1 in their Davis Cup World Group tie in Spain after Jamie Murray and Dominic Inglot were beaten in the doubles by Pablo Carreno Busta and Feliciano Lopez.
Murray and Inglot were second best throughout, losing 6-4 6-4 7-6 (7-4).
Britain must win both reverse singles rubbers on Sunday to be victorious in the tie on clay in Marbella.
Cameron Norrie and Liam Broady are due to play for GB but captain Leon Smith can select Kyle Edmund if he is fit.
The Australian Open semi-finalist was not chosen for Friday’s singles because of a hip injury.
Norrie is scheduled to play Albert Ramos-Vinolas before Broady faces Roberto Bautista Agut.
Sunday’s singles matches are live on BBC Two and the BBC Sport website from 10:00 GMT.
Britain fail to build on Norrie’s victory
The momentum appeared to be with Britain in this first-round tie after world number 114 Norrie came from two sets down to shock Bautista Agut in Friday’s second singles rubber.
However, they were always trailing in the doubles after Inglot was broken in the opening game and the British pair failed to sustain any pressure, creating only one unconverted break point in the match.
Inglot in particular struggled when serving and returning and was responsible for eight of Britain’s nine double faults.
Norrie and Broady – or Edmund if he comes in – face a monumental task to turn this tie around.
Spain captain Sergi Bruguera can bring in world number 10 Carreno Busta for the singles, while all five players in their squad are ranked in the top 40. Spain have won 27 of their past 28 Davis Cup ties on clay.
The losers of the tie will face a relegation play-off in September to stay in the World Group in 2019.