With the visitors heading into the final day with a 2-1 lead, Fritz Wolmarans put up a solid fight against fancied Turkish No 1 Marsel Ilhan.
The South African, ranked 350 places below his opponent in the ATP singles list, fought back from two sets down but was narrowly edged in a tight contest, with Ilhan clinching a 6-2 6-4 6-7 4-6 8-6 victory.
Captain Earl Grainger made a late change to the SA line-up, replacing Tucker Vorster with Ruan Roelofse for the deciding match against Turkish teenager Cem Ilkel.
Roelofse, who won the doubles rubber with Raven Klaasen on Saturday, lost control in the latter stages of the encounter after repeatedly arguing with match officials.
Ilkel took advantage of his apparent lapse in concentration to close out a hard-fought 7-6 6-7 5-7 7-6 6-4 win.
The South Africans will face Ireland in a relegation playoff at home in July, in an attempt to retain their place in Group 2 of the international team competition.