Canadian Eugenie Bouchard tumbled out of contention at the WTA Finals on Wednesday after a 6-1, 6-3 loss to Ana Ivanovic.

The Westmount, Que., native, who slipped to 0-2, will play Serena Williams in her final round-robin match of the tournament.

Williams was hammered 6-0, 6-2 by Simona Halep on Wednesday in one of the most lopsided losses of the star American's career.

Ivanovic had lost both her previous matches against Bouchard, at Wimbledon last year and this year's Australian Open quarter-final. However she cruised through the first set, winning all but two points when getting her first serve into play.

At the end of the set, Bouchard's coach Nick Saviano had to give his charge a pep talk, urging her to show more enthusiasm and fight, and the Canadian responded with a much more competitive showing in the second frame.

It was the first WTA Finals tournament for Bouchard, who made the semifinals of three Grand Slams this season, but she said she didn't feel overwhelmed by the experience.

"I've been asked a few times about it being my first time here," she said. "That never crossed my mind. I've done a lot of first things this year. You have to do everything first at some point in your life. I just was excited to come here. I see it as the fifth Grand Slam."

The key moment arrived in the seventh game, when Bouchard saved five break points but double faulted on the sixth, handing Ivanovic the break. The Serb went on to take the victory that put her back in the running for a semifinal berth.

Serena Williams embarassed

The last time Williams managed to win just two games in a WTA Tour or Grand Slam match was in 1998 when she was just 16.

"Embarrassing describes the way I played today," Williams said. "Very embarrassing."

The loss in the round-robin match snapped Williams' 16-match winning streak at the year-end championships, where she is the two-time defending champion.

"My forehand was off today," Williams said. "It's obviously gone on an early vacation. My serve was at best at the 10-and-under division of juniors."

The fourth-ranked Halep had never before beaten a player ranked in the top 3. In her previous two matches against Williams, both last year, the Romanian had won a total of seven games.

For a player who was ranked No. 47 two years ago, Wednesday's win over No. 1 Williams represented a new career high.

"It was my best match of my life," Halep said. "I played unbelievable shots. It means a lot this match. At an important time I played really well, and after today my confidence will be more high."

Halep, runner-up at this year's French Open, beat Bouchard in her opening match and moves to 2-0 in the Red Group. Williams slips to 1-1.

Williams' defeat jeopardized her chances of finishing the year as the top-ranked player. Had she won Wednesday, the only way she could have lost the No. 1 spot is if Maria Sharapova won the title.

Now, just reaching the final may be enough for the Russian, depending on the result of Williams' match against Bouchard on Thursday.

Williams was surprised by Halep's performance, saying "she has never played like this before."

"To be frankly honest, I am looking forward to our next meeting because she is going to make me go home, train hard and particularly train for her," Williams said.

In Thursday's matches in the White Group, Carolina Wozniacki meets Agnieszka Radwanska in a clash of two players who won their opening matches, while Sharapova faces Petra Kvitova.