Tennis: Sluggish Serena Williams downs Safarova in Hopman Cup thriller

The promised "two thousand times better" improvement did not materialise as a sluggish Serena Williams eked out a narrow 6-3 6-7(1) 7-6(6) win over Lucie Safarova at the Hopman Cup in Perth on Thursday.

Williams belted 41 winners, eight more than Safarova, but also committed 46 unforced errors in the see-saw contest.

"I just never give up," a tired-looking Williams said in a courtside interview. "I've been through so much in my life on the tennis court. I just keep fighting and keep doing the best I can."

After her shock straight sets defeat by Eugenie Bouchard on Tuesday, Williams had warned she could play "two thousand times better" but the improvement did not show against a gritty Safarova.

"I'd love to do a little better," said Williams. "I missed a few shots. I was not aggressive. Lucie played really, really well. She was aggressive. She kept hitting a lot of winners.