Nadal faces another epic in US Open quest

Rafael Nadal has taken a long, hard road in his quest to defend his US Open crown.

The 32-year-old Spaniard finished his quarterfinal victory against Dominic Thiem at 2am on Wednesday morning, after a brutal five-set slog that lasted four hours and 49 minutes.

That epic confrontation saw Nadal bounce back after losing the first set to love. And while he rallied to play some brilliant tennis, he also had to rely on unforced errors from his Austrian opponent to progress.

That victory followed four-setters against Nikoloz Basilashvili and Karen Khachanov. As a result, Nadal has clocked up almost 16 hours on the court, three and a half hours more than his semifinal opponent Juan Martin del Potro.

The last time the pair faced each other was back in July, when Nadal came back from two sets down to progress to the final four of Wimbledon. That match lasted 12 minutes shy of five hours, meaning fans could be in for another epic.

It's a challenge Del Potro is more than up for.

"It could be another big battle just as at Wimbledon," Del Potro said.

"I like to play always with the No. 1 of the world, doesn't matter the tournament or the conditions or the weather."

Awaiting the victor will be either Novak Djokovic or Kei Nishikori.

Djokovic has had a fairly smooth path to the final four, disposing of Richard Gasquet, Joao Sousa, and John Millman - the world number 55 who knocked out Roger Federer - in straight sets.

Playing in an incredible 11th consecutive US Open semifinal, Djokovic will be determined to go all the way to the title for just the third time in his career.

He has a superior head-to-head record against Nishikori, winning 14 of their 16 clashes, but the last time Nishikori defeated Djokovic was in 2014 - at Flushing Meadows in the semifinals.

"When Kei is on, he's a top-five, top-10 player," Djokovic said.

"He has a great two-handed backhand, great footwork and is one of the quickest players on tour."

Williams eyes home glory

In the women's semifinals, Serena Williams is aiming to win her first Grand Slam since giving birth to her daughter in September last year. She faces Latvia's Anastasija Sevastova, who is making her first appearance in the final four of a Grand Slam, but ousted defending champion Sloane Stephens in the quarters.

If Williams does live up to her favorites tag, Flushing Meadows could be set for an all-American final, with Madison Keys aiming to navigate her way past Naomi Osaka.

js/mp (AFP, AP)