Cape Town- Top-ranked Serena Williams overcame a stiff challenge in the opening set for a 7-6 (5), 6-2 win over Camila Giorgi on Saturday to give the United States a 1-0 lead over Italy in a Fed Cup World Group playoff.
Neither player broke serve in a highly competitive first set, which was only decided when Giorgi's forehand clipped the top of the net on Williams' first set point.
Williams improved to 19-0 this year and 15-0 for her career in Fed Cup.
The second match in the best-of-five series featured 57th-ranked American Lauren Davis playing No. 15 Sara Errani.
The winner returns to the World Group and can compete for the Fed Cup trophy next year while the loser will be relegated to the World Group II.