SAN DIEGO, CA, USA - Defending champions Italy are on the verge of a third Fed Cup title in five years, after Francesca Schiavone and Flavia Pennetta won the opening two singles rubbers against the United States in San Diego on Saturday.

In the first game of the tie, two aces made a promising start for American Fed Cup debutante Coco Vandeweghe. However, the 18-year-old followed up with two double faults to give Schiavone an early edge. Another break in the fifth game ensured Schiavone's supremacy in the first set, and when the French Open champion broke again in the first game of the second, she seemed on course for a rout.

To her credit, though, 114th-ranked Vandeweghe drew level for 4-4. But 30-year-old world No.7 Schiavone immediately broke again before closing the match out on serve, 62 64.

"I was ready for everything today, so it was tough for her," said Schiavone. "I started really well, particularly the first set. Then I went a little bit down, but the way that I was playing was good. I was aggressive, good defence, a good serve."

"She's Top 10 in the world for a reason," said Vandeweghe. "She plays well. She competes well. She has variety, lots and lots of variety to her game, different looks. That's what took me a little bit of time, but it's all a learning experience."

Playing as the US No.1 in the absence of the Williams sisters, 58th-ranked Bethanie Mattek-Sands reeled in 3-0 and 5-1 deficits in the opening set of the second rubber, but Pennetta proved too steady in the tight spots.

Having saved a set point in the twelfth game, the Italian was helped by a couple of unforced errors deep in the tie-break. Service breaks were exchanged early in the second set, but trailing 3-2 Mattek-Sands required medical treatment for cramps. Pennetta broke twice more to close it out, 76(4) 62.

"I'm really happy because today was not easy," said Pennetta, who is currently ranked No.23. "I think I didn't play my best tennis, but I was running and running and fighting, and try to do my best all the time.

"When you play for your country, when you have a lot of people outside screaming and cheering for you, it's easy to try to fight until last point."

Mattek-Sands and Schiavone face off in the first reverse singles on Sunday. Should the American keep the tie alive, US captain Mary Joe Fernandez could switch in the more experienced - and higher-ranked - Melanie Oudin to replace Vandeweghe against Pennetta.

The US is bidding to win the Fed Cup for the 18th time, but first since 2000.