Former world number one Serena Williams has said that she is starting a “long comeback”. Especially after losing 6-3 2-6 6-3 to Czech Petra Kvitova in Cincinnati.

She lost in the second-round just a few days after her heaviest career defeat, a 6-1 6-0 loss to Britain’s Johanna Konta in the Silicon Valley Classic first round.

“I’m still at the very beginning,” said the 23-time Grand Slam champion. “I’m just going to continue to work hard, and hopefully I’ll start winning more matches.”

Following the crushing defeat to the Briton, the 36-year-old American withdrew from last week’s Rogers Cup in Canada for “personal reasons”. She later clarified that she had been struggling with post-natal emotions.

The two-time Cincinnati champion, had returned to the women’s tour earlier this year after giving birth to her daughter. She impressed many during her opening match at the Western & Southern Open. Serena Williams smashed eight aces en route to a 6-1 6-2 win over Australian world number 23 Daria Gavrilova.

Even after losing the first set to two-time Wimbledon champion Kvitova, Williams refused to give up. she fought back to level the match at 2-6. Both players broke each other’s serve at the start of the third set. However, the eighth seed broke again at 4-2 and proceeded to hold serve to progress to the third round.

“It was a pleasure to share the court with Serena, she’s such a champion,” said Kvitova. “We are both coming back – from injury, from motherhood – so it’s something really special to play her.”

This will undoubtedly be a setback for the 36-year old as she prepares for the US Open. The Grand Slam at Flushing Meadows usually heralds the end of the Grand Slam season. Along with Williams, Britain’s Kyle Edmund also crashed out of the tournament, losing to Denis Shapovalov.