NEW YORK – Play has moved into the second round of the 2016 US Open and, among other storylines, it started with an upset on the women's side.

Ranked No. 74 in the world, Caroline Wozniacki hasn't found the same level of success since she was the world's No. 1 player in 2010. However, the 26-year-old native of Odense, Denmark, entered New York this week on a mission. Having reached the final in 2009 and again in 2014, the US Open has been good to Wozniacki. Her opening-round matchup, however, didn't remind many of her better days as she narrowly defeated American Taylor Townsend. For skeptics, they could have easily dismissed Wozniacki's chances on Wednesday when she took on No. 9 seed Svetlana Kuznetsova.

Those skeptics would be proven wrong. Wozniacki pulled off the upset, defeating Kuznetsova 6-4, 6-4 to advance to third round of play.

On paper, it wasn't a dominant victory for Wozniacki. In fact, the most compelling stat in the match was her 62 percent winning percentage on first serve. In addition, the native of Denmark made fewer errors than her Russian counterpart, committing just 17 unforced errors to Kuznetsova's 31.

Waiting for Wozniacki in the third round is Romania's Monica Niculescu who rolled over her second-round opponent, Ana Bogdan, also of Romania, 6-0, 6-1.

In six previous matchups, Wozniacki has yet to lose to the No. 54 ranked Nicolescu.

On the men's side, though, there was a bigger upset.

World No. 6 Milos Raonic has been celebrating a great 2016 after, among other accomplishments, becoming the first Canadian male to reach a grand slam final, doing so at Wimbledon back in July. He most recently reached the semifinals at the Western & Southern Open in Cincinnati and was looking to make the most of his time in New York this week. Unfortunately for him, American Ryan Harrison had something to say about that.

After cruising past German Dustin Brown in the opening round, Raonic was ousted as Harrison defeated him 6-7(4), 7-5, 7-5, 6-1, sending the Canadian home much earlier than anticipated.

Among other things, cramps contributed to Raonic's shocking loss.

“It was just catching me all over,” Raonic said. “I started getting small cramps where I couldn't hold the racket. I couldn't switch grips from one point to the next. There were a few points where I would hold the racket with my left and try to stretch out my right hand in between shots - and that's not going to work.” Later, it appeared that his legs were affected as well.

Whichever way you look at it, though, this was not what the Canadian or his hometown fans were expecting as the world's No. 6 seed was expected to go deep in the tournament at Flushing Meadows. After all, with Federer out for the year, Djokovic potentially nursing an injury, Murray having played so much this summer and Nadal's uncertainty with his own health, the time was now for Raonic to shine.

Ranked No. 120 in the world, Harrison certainly deserves credit for ousting Raonic. The two had split their previous two meetings entering Wednesday's match. But on this day, the native of Shreveport, Louisiana, played at a higher level, going back-and-forth with the Canadian before dominating the fourth and deciding set. The most glaring stat of the match, however, was the unforced errors. Harrison committed 33 but Raonic dug himself a bigger hole as he committed 62 with his injury contributing to that total.

For Harrison, it goes without saying that the win was arguably the biggest of his career. Waiting for the 24-year-old in the third round, though, is Marcos Baghdatis of Cyprus.

Ranked No. 44 in the world, Baghdatis met Harrison twice before with each player winning once.