Lindsay Davenport tasted defeat for the first time in a year on Saturday, losing 6-3 7-5 to second seed Jelena Jankovic in the China Open semi-finals.
World number three Jankovic will be chasing her fifth title of the season in Sunday's final with Hungarian sixth seed Agnes Szavay, who silenced a partisan home crowd by crushing China's Peng Shuai 6-1 6-2.
Jankovic was a break down in both sets but Davenport made 20 unforced errors in the 1-1/2 hour contest and the Serb battled back to beat the American for the first time.
It also avenged a defeat by the former world number one in Bali last week.
"This time it was a different story, I tried to play tight and tried to move her around," Jankovic told reporters.
"I tried not to give her the shots she likes because it's amazing how clean she hits the ball."
Davenport had won eight successive matches and last week's Bali tournament on her return to tennis after a year in retirement, and just three months after giving birth to her son.
"It's been so much tennis for me over the last two weeks and for the first time my legs felt heavy and I couldn't move as quickly as I would have liked to," said the 31-year-old.
"But it's been a wonderful couple of weeks, I've really enjoyed it and have exceeded my expectations."
The match became a little bad-tempered late in the second set when Davenport complained to the umpire after being hit by a ball Jankovic had tossed high into the air in frustration.
"There's no room to act like you're 12 years old, this is the pros," Davenport said.
"I think at 5-5 in the second set when you're about to serve, you shouldn't have to worry about being hit by the ball out of play."
Jankovic said she had apologised to Davenport on court.
"I was really frustrated but it was an accident," she said. "I really apologise, I didn't do it on purpose for sure."
SZAVAY PRESSURE
Local hope Peng had beaten Martina Hingis and Amelie Mauresmo on her way to a second successive semi-final here but Szavay put her under pressure from the start.
The Hungarian teenager, who reached the U.S. Open quarter-finals earlier this month, broke in 21-year-old Peng's first service game and wrapped up the first set in less than half an hour when the Chinese double faulted.
Peng had come from a set down against Mauresmo but, perhaps because of the strain of reaching the semi-final in singles and doubles, found no way back in an equally one-sided second set.
Szavay, who has risen from 207th to 23rd in the world this year and won her first WTA title in Palermo in July, will be playing her third final of the season in her first match against Jankovic.