Caroline Wozniacki vs. Peng Shuai: US Open 2014 Women's Semifinal Score, Results

Caroline Wozniacki continued her return to the elite ranks of women's tennis Friday with a win over Peng Shuai in the 2014 U.S. Open semifinals, but the mood was far from celebratory at the match's conclusion.

Due to severe cramping, the Chinese underdog was forced to retire while trailing 7-6(1), 4-3. It was an extremely competitive contest throughout, but it didn't end the way either player would have wanted it to.

This marks the second Grand Slam final appearance of the Danish star's career, and the first since she made it all the way to the end at the 2009 U.S. Open.

Although Wozniacki entered Friday's semifinal match as the clear favorite to advance, she knew in the wake of her quarterfinal win over Sara Errani that Peng would pose an interesting challenge, per WTATennis.com.

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She's been playing well. She's playing aggressively. She's strong from both sides. She's been serving well. It's going to be a difficult match. It's definitely going to be a different match than against Sara today. Sara runs a lot of balls down and doesn't make many mistakes, but Peng is closer to the baseline and going for her shots more. It's going to be a hard one, but it's going to be fun.

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Having struggled so much over the past couple years, Wozniacki was clearly excited to be back in contention at what has traditionally been her best Grand Slam tournament by far:

In order to advance to the final, Wozniacki would have to take two sets off Peng, who entered the match having not dropped a set in the entire tournament, according to tennis journalist and author Richard Ingham Evans:

Based on this stat courtesy of WTA director of communications and publications Kevin Fischer, Peng's play at the U.S. Open leading up to Friday's tilt was quite a revelation:

One school of thought entering the match was that Peng's unorthodox style might give Caro some fits. As pointed out by ESPN's Howard Bryant, there is no distinction between the Chinese star's forehand and backhand:

That didn't seem to bother Wozniacki much early on, though. According to Craig O'Shannessy of The New York Times, Wozniacki took a 2-1 lead due largely to her aggressiveness against Peng's ground strokes:

The opening set was largely a war of attrition as Wozniacki and Peng traded three service holds apiece to start. It was the Chinese underdog who would draw first blood, though, by breaking a shaky service game from Wozniacki, per Douglas Robson of USA Today:

That lead was short-lived, however, as the 28-year-old was broken right back by Wozniacki to make it 4-4. According to Ben Rothenberg of The New York Times, it ended an impressive run of service holds for Peng in New York City:

After consolidating with a hold, Wozniacki had a chance to take the set by breaking Peng for a second time. The pressure didn't get to Peng, though, as she held as well to make it 5-5.

Peng then used the momentum gained from that hold to break Wozniacki once again and put herself in position to serve for the set. Per Robson, the Dane was irate with herself for squandering an opportunity:

Rather than allowing things to snowball, Wozniacki channeled that frustration and used it to battle back and force a tiebreak by breaking Peng in return.

It is clear that Peng's failure to serve out the set demoralized her to some degree as Wozniacki proceeded to dominate the tiebreak. According to O'Shannessy, savvy and strategic play is what set Wozniacki apart from Peng in the first set:

It would have been easy for Peng to close up shop after such a tough first set, but she refused to go away. The unheralded player held serve to start the second set and then surprisingly broke Wozniacki to go up 2-0 in quick fashion.

Peng could have taken firm control of the set with another hold, but Caro buckled down and struck back with a break of her own. It was a battle during the ensuing service game as it went to deuce on three occasions, but Wozniacki finally held to even the score at 2-2.

As it turns out, Wozniacki's laboring may have had something to do with her health. Per Stuart Fraser of Daily Mail, Wozniacki took pills for an illness in between the first and second sets:

Despite her potential issues, Wozniacki continued to fight and regained control of the set 3-2 by breaking Peng again. The momentum continued to flow after that as Wozniacki held to win her fourth consecutive game and come within two of taking the match.

Peng desperately needed to hold in order to stop the run and maintain a realistic chance of coming back. Although she let two game points slip away, she converted the third to make it 4-3.

With Wozniacki's service game knotted at 30-30, it appeared as though Peng started to cramp up. While Peng could barely move, Wozniacki double faulted and handed Peng break point.

Unfortunately, Peng seized up and couldn't move after that point, according to SI Tennis:

That resulted in the trailing underdog being escorted off the court for further evaluation, per Live Tennis:

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Peng needs two people to help her off the court. Such a shame after her great run. pic.twitter.com/VWb2hvI7a4

— Live Tennis (@livetennis) September 5, 2014"

The decision to allow Peng to get treatment was a controversial one since she was tended to on the court for several minutes before finally being granted a three-minute medical timeout. Peng returned after roughly nine minutes and she was not penalized despite being tended to for so long.

According to Jon Wertheim of Sports Illustrated, that decision wasn't fair to Wozniacki:

Peng continued to fight for a few more points, but the cramps returned and she simply could not continue. Although she didn't want to quit, she had no other choice. In a true show of sportsmanship, Wozniacki checked on her as she cried on the court:

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Peng down again, crying. Wozniacki, trainers with her. pic.twitter.com/Nmvim7FWmr

— Live Tennis (@livetennis) September 5, 2014"

According to BBC's Russell Fuller, Peng ultimately had to be taken from the court in a wheelchair in what was certainly a heartbreaking moment:

Wozniacki is most definitely playing her best tennis since being ranked No. 1 in the world back in 2010. Her defensive style has carried her through the tournament, and it was certainly her bread and butter against Peng.

As well as Wozniacki is performing, though, the biggest test lies ahead. The 24-year-old star will meet either world No. 1 Serena Williams or Russian upstart Ekaterina Makarova in the final. Serena is clearly a huge favorite to advance, and she would play Goliath to Wozniacki's David in the final as well.

Wozniacki and Williams are polar opposites on the court, but they are good friends off it. They know each other's tendencies well, and it will be a compelling final to say the least.

Serena beat Wozniacki in their most recent meeting at the Western & Southern Open a couple weeks ago, but it was a three-set thriller.

Williams has been vulnerable in Grand Slams this year as she is without a major title in 2014. Wozniacki will have to play a near-perfect match to beat her, and it is tough to imagine Williams allowing her 18th career Grand Slam championship to slip away once again.

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