Li Na of China serves to Sorana Cirstea of Romania during their women's semi-finals tennis match of the Rogers Cup tennis tournament in Toronto August 10, 2013. The image is an in-camera, multiple exposure photograph. [Photo/Agencies]

TORONTO - Li Na, the world No 5 ranked player, was stunned by No 27 ranked Sorana Cirstea of Romania in the semi-final of the Rogers Cup on Saturday afternoon. Cirstea won in straight sets, 6-1, 7-5 (5).

Li, who was runner-up to Petra Kvitova in Montreal last year, trailed Cirstea for most of the first set.

The Chinese failed to hold serve in her second service game, giving the Romanian a 3-1 lead. Li was once again broken in her next service game, unable to handle the deep returns and baseline winners of her 23-year-old opponent.

Cirstea continued to dominate, wrapping up the first set 6-1 in only 21 minutes.

During the player break between sets, Li spoke to her coach and husband to offer words of encouragement.

Li stormed out to a 4-1 lead in the second set after breaking Cirstea in her first service game.

At this point, Cirstea strategically took advantage of her coaching timeout and recovered nicely to win four straight games and take a 6-5 lead. Cirstea even had an opportunity to serve out the game with two match point opportunities in the following set, but Li's determination forced a tiebreak.

During the tiebreak, momentum seemed shift to Li's side, storming out to a 4-1 lead. Cirstea settled down and controlled the rest of the tiebreak, winning six of the next seven points.

The tiebreak, set and match concluded when Li recorded her sixth double fault of the match to lose 7-5 in the tiebreak game.

"I think I still have chance, but today I didn't catch the chance. I just lose the chance to come to the final set," said Li of the second set.

Li blames herself for the loss, but also credits Cristea's play.

"She got a lot of confidence right now," said Li. "Sometime I was feeling she couldn't hit a winner, but the ball come to you as a winner. It's very tough.  But, I mean, nothing to say, because today I didn't play best of tennis, but at least I try on the court."

With the victory, Cirstea reaches her third career WTA final and first in nearly five years. She won the Tashkent Open in Uzbekistan when she defeated German Sabine Lisicki in October 2008.

"Everything is based on hard work.  Everyone can see that I have been doing some great steps in the right direction," said Cirstea after the match. "I'm just very excited to keep these things going and just make out of this mentality a habit."

Her opponent in Sunday's final will be either world No 1 ranked Serena Williams of the United States or No 4 Agnieszka Radwanska of Poland.