Serena Williams quit her Dubai Open semi-final with an arm injury on Friday while trailing Serbia's Jelena Jankovic 6-0, 4-3.
The second-seeded American, who also defaulted her quarter-final match at the last event she played in Paris earlier this month, opted to pull out after a discussion with a courtside trainer.
Jankovic will play top seed Lindsay Davenport in the final of the $1 million event after Davenport overcame a stomach upset and a strong challenge from Switzerland's Patty Schnyder to win 4-6, 7-5, 6-1 earlier in the day.
It had been clear from the start that Williams was in difficulty. She did little more that roll the ball into play on her serve, and was unable to maintain any rallies.
Williams won just two points in the first two games, and dropped her serve a second time with a double-fault.
After another break for 5-0, Williams finally held but was unable to convert two break points and Jankovic served out the set.
After dropping her serve again to begin the second set, Williams received a warning for smashing her racket.
LENGTHY DISCUSSION
As the errors flew from her racket, a frustrated Williams called for the trainer and after a lengthy discussion retired from the match.
Top seed Davenport was ultimately too strong for her opponent in the other semi-final although initially Schnyder, who beat world number one Davenport in their last meeting, took advantage of a lethargic performance in the first set.
Davenport had no rhythm and made a succession of errors, eventually double-faulting to give the Swiss left-hander a 3-1 lead.
Even though Davenport managed to break as Schnyder served for the set at 5-3, she dropped her serve again when the number eight seed won a long rally at the net to take the set.
"In the first set I felt so wild," said Davenport. "I was trying so hard and the balls were just flying on me. It was so hard keeping balls in.
"Finally I got my shots inside the lines and didn't go for so much and I was able to play a little bit more percentage tennis."
Davenport was the first to break in the second, for 2-1, but played a poor game at 3-2, double-faulting three times and allowing Schnyder to level at 3-3.
Schnyder fought off two break points in the next game before Davenport called for the trainer and received medicine for her stomach.
"I was up 2-1 in the second and for the next four games I was feeling really nauseous, like I was going to get sick," said Davenport.
"It's hard when there's people around because you really don't want that to happen. I was trying to keep the points short for a few games there."
POSITIVE TENNIS
The American began to strike the ball more positively, breaking to lead 6-5 and then again to begin the deciding set.
Hitting deep to force errors from Schnyder, Davenport took almost complete control, breaking again to lead 4-1 and dropping just one point in the final two games.
"I was never in too much danger," said Davenport. "At 4-4 I held pretty easily and then for 7-5.
"I was just able to eke out the second set, and the third set I just played a lot better and she started to make a lot more unforced errors."
Schnyder admitted she became frustrated at not being able to close out the match in the second set.
"I had a good chance there in the second," she said. "I sensed the moment but my shots were not there.
"I was really frustrated because it was time to win the match but I couldn't do it. In the third I felt my serve was slipping away and her game was better and better, and that's not nice to feel."