BRINDISI, Italy -- Serena Williams thought she was ready for the clay-court season.
As it turns out, the top-ranked player still has a long way to go toward finding the form that could propel her to a 20th Grand Slam title at the French Open.
"Today has been a big eye-opener," Williams said after coming back from a set down to post an error-filled 4-6, 7-6 (3), 6-3 win over Sara Errani on Sunday in a Fed Cup playoff against Italy.
"I need to go home and really train," Williams said. "I'm totally not as ready for clay-court season as I thought I was. ... Next time I'll be really, really ready and I'll know what to expect. Now I'm in the mindset of, 'You know what, I'm not on hard court.' I'm playing like I'm on hard court and I'm not. So I have to play and be ready to hit a thousand shots if necessary."
Williams also won her opening singles match Saturday, but the U.S. sorely missed her sister Venus Williams, who withdrew from the U.S. team due to a personal matter. Also missing was rising star Madison Keys, who declined an invitation from U.S. captain Mary Joe Fernandez.
"Everybody that could be here was here," Fernandez said.
Italy returns to the World Group and can compete for the Fed Cup trophy next year while the U.S. is relegated to World Group II.
It was Williams' first career loss in the Fed Cup, dropping to 16-1 -- 13-0 in singles and 3-1 in doubles.
Errani and Pennetta celebrated by throwing water at each other and captain Corrado Barazzutti, and dancing on the red clay court.
Italy has now beaten the U.S. five consecutive times, including back-to-back finals in 2009 and 2010.
"When we won those two finals everyone said, 'Well, the Williamses didn't come,'" Barazzutti said. "So having Serena here makes this a little bit sweeter. We showed we're one of the best teams in the world no matter who we play against."
In her singles match, Williams held a massive 70-7 lead in winners, but she committed nearly three times as many unforced errors as the 15th-ranked Errani -- 61-23.
Until the very end, Williams struggled to dictate play against someone who had never before presented her with serious problems.
"I don't think I ever really got the hang of it," Williams said. "I really struggled today in the wind, on both sides. I don't know what side was worse for me. Usually I'm able to adjust, and it's a little disappointing that I wasn't able to adjust sooner."
Still, Williams improved to 20-0 this year in singles.
But Williams usually dominates Errani by taking advantage of the Italian's weak serve. This time, the wind prevented her from stepping too far into the court.
The Circolo Tennis Brindisi is located next to the southern city's port, and a sharp breeze was blowing off the bay.
Williams and Errani often had to catch their tosses and start their service motions over again, or delay play when the wind whipped clay into their eyes between points.
"The wind helped me," Errani said. "Against a player like her, it favored me."
With the sellout crowd of 4,000 chanting her first name, Errani served for the match at 5-4 in the second set but Williams played solidly and then the American surged to a 6-1 lead in the tiebreaker and pushed it to a third.
There were four consecutive breaks of serve to open the third set, and it was tied 3-3 before Williams finally surged ahead.
"I had a great experience here in both singles and doubles," Williams said. "I realized there are some things I want to work on. So I'm going to go home, train a little bit and get ready for the rest of the season."
Netherlands 3, Australia 1
'S-HERTOGENBOSCH, Netherland -- Arantxa Rus staged a comeback Sunday to beat Jarmila Gajdosova 0-6, 7-5, 7-5 and seal victory for the Netherlands over Australia in their Fed Cup World Group playoff. With only the doubles match to complete, Rus' victory gave the Netherlands an unassailable 3-1 lead and ensured the Dutch will return to the World Group for the first time since 1998.
The win for Rus looked a long way off after Gajdosova took just 25 minutes to claim the first set. Rus finally won her first game 45 minutes into the match to make it 2-1 in the second set to spark the comeback and complete the Netherlands' seventh straight Fed Cup victory.
The win was vindication for coach Paul Haarhuis' decision to play the experienced Rus instead of higher-ranked Richel Hogenkamp in the singles.
Australia, a losing semifinalist last year, was missing former U.S. Open champion Samantha Stosur, who pulled out on the eve of the weekend tie after aggravating an Achilles tendon injury.
Belarus 3, Japan 2
The result means Belarus will return to World Group II in 2016 for just the third time, while Japan will remain in Asia/Oceania Zone Group I.
The Associated Press contributed to this report.