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 .
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 .