article: Twice French Open champion Serena Williams said her struggle to beat Sara Errani in the Fed Cup on Sunday had been a real 'eye-opener' as the claycourt season gets into full swing. World No 1 Williams eventually prevailed 4-6 7-6(3) 6-3 against the dogged Italian to take her career record over her to 8-0 but the American was not impressed. The US  were beaten 3-2 as Williams and Alison Riske were thrashed 6-0 6-3 in the doubles rubber by Errani and Flavia Pennetta, meaning they were relegated to World Group II. American tennis star Serena Williams fought back to beat Italian Sara Errani in the Fed Cup play-off on Sunday . Tough weather conditions made it difficult for both players who had to keep on re-tossing their serves . Errani gave Williams a real scare but in the end the world No 1's power proved to be too much . 'Today has been a big eye opener,' Williams said afterwards. 'I'm totally not as ready for the claycourt season as I thought I was. 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, 33, won her 19th singles grand slam at the Australian Open and her dominance has raised talk of her claiming all the majors this year. The French Open has been her least successful of the four though despite claiming the title in Paris in 2002 and 2013. Her doubles defeat on Sunday blotted an otherwise flawless Fed Cup record and left the US facing a battle to get back amongst the elite nations next year. 'We have to work harder,' US captain Mary Joe Fernandez said. 'We came close today and need to just keep plugging away. 'The good news is that we have a lot of players in the top 100 and, hopefully, we can get two wins next year and get back into the World Group.' Williams congratulates Italy captain Corrado Barazzutti after competing in America's doubles defeat .
highlights: Serena Williams struggled to beat Sara Errani during  Fed Cup clash .
  World No 1 Williams eventually defeated Errani 4-6 7-6(3) 6-3 .
  Williams lost doubles match alongside Alison Riske 6-0 6-3 .
prediction: French Open champion Serena Williams 
   a 
   No 1 
   4 - 6 7 - 6 (3) 6 - 3 
   her career record 
   8 
   the American 
   US 
   3 
   2 
   Williams and Alison Riske 
   0 6 
   Errani and Flavia Pennetta 
   to World Group II 
   back to beat Italian Sara Errani in the Fed Cup play - off on Sunday . 
   The 
   in America' s doubles 
  .