US Open PHOTOS: Nadal overpowers Daniel, Federer struggles

Images from Day 4 of the 2017 US Open.

World number one Rafael Nadal came from behind to dispatch underdog Taro Daniel of Japan 4-6, 6-3, 6-2, 6-2 in front of a sold-out crowd at the US Open on Thursday.

Despite playing a marathon five-setter the day before, 121st ranked Daniel looked the fresher of the pair at the outset of the match, breaking Nadal to take a 5-4 advantage when the Spaniard dumped a forehand into the net.

He eventually won the set and appeared poised to deliver a massive upset.

But Nadal soon found the accuracy that had eluded him in the first set and his booming serve proved too much for the exhausted 24-year-old, who is now 0-6 against top 20 opponents in his career.

"All the matches are difficult, especially here where everyone wants to play their best," Nadal said in an on-court interview at the Arthur Ashe Stadium after the win.

"It's true that I didn't play very well tonight but it's also true that I'm through to the next round."

Nadal is now one step closer to a potential semi-finals match against third seed Roger Federer, who won his second consecutive five-set match earlier on Thursday.

"I am here to improve every day. I believe I can do it much better and I really feel I am going to do it much better," Nadal said.

Next up for the 31-year-old is a third round match against aggressive Argentinian Leonardo Mayer.

World number three Roger Federer survived his second scare in as many matches but hung on to defeat Russian Mikhail Youzhny 6-1, 6-7(3), 4-6, 6-,4 6-2 to reach the third round of the US Open on Thursday.

Federer, who also claimed a come-from-behind five-set victory in his first round match against 19-year-old Frances Tiafoe, took advantage of a clearly hobbled Youzhny, who appeared to suffer from muscle cramps midway throughout.

Despite looking at times like he might retire from the match, Youzhny put in his best performance against the Swiss.

But the former top 10 player's fate was all but sealed when he double faulted to hand the Swiss a 4-2 lead in the fifth set and later saw Federer's record against him improve to 17-0.

The match marked the first time the 36-year-old third seed had ever started a grand slam tournament with back-to-back five set matches, raising questions about whether he has the stamina necessary to win his 20th career grand slam.

"These five set battles are actually a lot of fun," Federer said during an on court interview after the match.

"I feel quite warmed up now," he added with a laugh.

Despite the win Federer looked nothing like the dominant player who won the Australian Open to kick off the year and later cruised through Wimbledon without dropping a set.

He committed 68 unforced errors and the back injury that kept him out of the Cincinnati Masters earlier this month appeared to limit his mobility.

Next up for Federer is Feliciano Lopez, who defeated fellow Spaniard Fernando Verdasco in four sets in their second round match.

Federer has defeated Lopez in all 12 of their previous meetings.

World number one Karolina Pliskova survived a scare to advance to the third round of the US Open with a 2-6, 6-3, 6-4 comeback win against local favourite Nicole Gibbs on Thursday.

The Czech, who reached the final at Flushing Meadows last year, was on the back foot against Gibbs before finding her range on serve.

Roared on by the Arthur Ashe Stadium crowd, Gibbs was nothing like the player who lost 6-0, 6-0 in their previous encounter in Sydney in 2015.

She bulldozed her way through the opening set as Pliskova struggled with her first serve.

The Czech faced a break point at 2-1 in the second set but Gibbs netted a backhand for what proved to be the turning point of the match.

"In the second set I started to serve better and get easy points with my first serve, which was much needed," said Pliskova.

"I'm happy I managed to get through."

She next faces Chinese 27th seed Zhang Shuai or Japan's Risa Ozaki.

Ukrainian fourth seed Elina Svitolina powered into the third round of the US Open with a 6-4, 6-4 win against Russian Evgeniya Rodina.

The 22-year-old, who had also reached the third round at Flushing Meadows in the previous two years, was barely troubled by her 89th-ranked opponent in a sun-kissed Arthur Ashe Stadium.

Svitolina lost focus in the second set at 5-2 when she allowed Rodina to pull a break back, but she held her following service game to wrap up the victory on the first match point with a backhand winner.

She next faces either American Shelby Rogers or Australian 25th seed Daria Gavrilova.