Caroline Wozniacki and Maria Sharapova were far from happy to be caught in the glare of the stadium lights at the WTA Finals in Singapore on Tuesday.

The third match of the tournament was held up briefly as both players complained of a lighting issue midway through their absorbing encounter.

Wozniacki emerged victorious in the three-hour marathon, but not before the Dane and her Russian opponent found conditions overhead a little too bright in the world No 8's 7-6 (4), 6-7 (5), 6-2 triumph.

"All of a sudden the light show starts going on and once that was turned off there were two bright lights right in the middle that stayed on," Wozniacki said.

"So it took a couple of minutes to turn them off and when I went over to the other side, they were turned on again. They weren't on from the start, so it felt a little strange."

The Dane was a set and a break up when she began to remonstrate with the umpire over the issue, a complaint met with a few boos from spectators.

Sharapova elaborated on the incident when pressed at her post-match news conference.

"I feel like the lights have been an issue the whole week leading up to the tournament. Every day, the light out on the stadium for practice has been different," the world No 2 said.

Singapore is hosting the WTA Finals for the first time and the venue has encountered a few teething problems in attempting to create an intimate atmosphere.

"The first day I practiced, I think it was Monday last week, it was like dark in the middle of the court and light on the sides ... and then the lights went out," said Sharapova.

"That happened for a couple of days. They ended up putting enough lights on the center but not enough on the sides. I still feel like there is not enough lights on the sides of the court.

"When you're running for a forehand you're actually in a shadow and then you get back in the court and you're in the light.

"That's quite different to (previous Finals host) Istanbul but maybe that's just the way it is."