CHARLESTON, S.C. -- No. 1 Serena Williams suffered her worst defeat in nearly two years on Tuesday, losing to No. 78 Jana Cepelova of Slovakia 6-4, 6-4 in the second round of the Family Circle Cup.
The loss, which came three days after Williams won the Sony Open in Miami for the seventh time, snapped her 28-match winning streak on clay. Her last loss on the surface came against No. 111 Virginie Razzano in the first round of the 2012 French Open.
Signs of an upset came early after Williams quickly fell behind 5-0 in her opening match here. She started slowly in nearly all of her matches in Miami, but this time she couldn't elevate her game to overcome Cepelova. Williams battled back to 4-5 in the first set, but Cepelova steeled her nerves to finally serve it out. Early in the second set, Williams called a medical timeout to have her left thigh taped. Cepelova responded with a flurry of drop-shot/passing-shot combinations that left Williams with few answers.
"I tried, but I just couldn't do any more," Williams said. "Physically, I just couldn't give any more."
Cepelova, who scored her first victory against a top-10 player, said she entered the match nervous and lacking belief that she could defeat Williams in their first meeting. But, like her idols Rafael Nadal and Martina Hingis, who was born in her hometown of Košice, the 20-year-old Cepelova stayed relentless with her game plan, moving Williams around the court and keeping her uncomfortable.
"She was a great counterpuncher," Williams said. "She hit a lot of balls back, and I really knew nothing about her game. So she played a really good game against me."
Williams, the two-time defending champion, chalked up her poor form to the cumulative effect of two incredible years of nearly nonstop play. Since the start of 2012, Williams has played 149 matches and won 20 titles, including 12 in the last 12 months. That's an unprecedented amount of play for the 32-year-old Williams, who was known for keeping a fairly limited schedule in her younger years, but increased her workload after she started working with coach Patrick Mouratoglou following the French Open loss two years ago.
"I'm really just dead," Williams said. "I need some weeks off where I don't think about tennis and kind of regroup. I've had a long couple of years, and I'm really a little fatigued."
Serena added: "I just think I've been training really hard and putting so much effort into every day for a couple of years now. I think sometimes taking a break is just can as important as training, and I haven't been really doing that so much."
Williams was upbeat talking to reporters. Her next scheduled tournament is the Madrid Open in May, giving her plenty of time to regroup. She'll need to get both her body and her mind right to defend her French Open title.
"I need some time off, so I'm going to kind of take a deep breath," she said. "I haven't had time, even in the offseason. I went straight to training and there's just been so much in several years. So I just need to take a deep breath and regroup, and I think actually it'll really help me for the rest of the clay‑court season."