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 only blemish on Williams' record this year came when she withdrew before the Indian Wells semifinals last month with a knee injury. Serena Williams handed USA the lead against Italy with a first victory in the Fed Cup . The world No 1 shakes hands with US captain Mary Joe Fernandez after putting USA ahead . 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. Giorgi was a surprise choice by captain Corrado Barazzutti for Italy's second singles spot over Brindisi-born Flavia Pennetta but the 23-year-old showed surprising poise and was even able to match Williams' power in the opening set. Williams defeated Camila Giorgi 7-6, 6-2 on the clay in Brindisi, Italy . Williams was matched shot for shot by Giorgi in the first set before breaking away in the second . Giorgi matched Williams with 17 winners apiece in the first set - which lasted more than an hour - while Williams committed 18 unforced errors to Giorgi's 15. Unable to impose her game, Williams appeared frustrated and kept shouting "Come on!" to herself in angrier and angrier tones as the first set wore on. And she consistently applauded, using one hand and her racket, when Giorgi blasted winners by her. But Williams played solidly in the tiebreaker and then surged ahead early in the second set.
USA face Italy in a Fed Cup World play off in Brindisi . World No 1 Serena Williams defeated Camila Giorgi 7-5, 6-2 . Lauren Davies will play Sara Errani in the  second singles match .