US Open Day 12 - Men's semi-finals at a glance

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Hard won: Rafael Nadal celebrates his US Open quarter-final victory over Austrian Dominic Thiem

Men's semi-final matches on Friday, the 12th day of the US Open (x denotes seeding):

Rafael Nadal (ESP x1) v Juan Martin del Potro (ARG x3)

Head to head: Nadal leads 11-5

2018 Wimbledon Grass QF Nadal 7-5, 6-7 (5/7), 4-6, 6-4, 6-4

2018 French Open Clay SF Nadal 6-4, 6-1, 6-2

2017 US Open Hard SF Nadal 4-6, 6-0, 6-3, 6-2

2016 Rio Olympics Hard SF Del Potro 5-7, 6-4, 7-6 (7/5)

2013 Shanghai Hard SF Del Potro 6-2, 6-4

2013 Indian Wells Hard F Nadal 4-6, 6-3, 6-4

2011 Davis Cup Clay F Nadal 1-6, 6-4, 6-1, 7-6 (7/0)

2011 Wimbledon Grass R16 Nadal 7-6 (8/6), 3-6, 7-6 (7/4), 6-4

2011 Indian Wells Hard SF Nadal 6-4, 6-4

2009 US Open Hard SF Del Potro 6-2, 6-2, 6-2

2009 Montreal Hard QF Del Potro 7-6 (7/5), 6-1

2009 Miami Hard QF Del Potro 6-4, 3-6, 7-6 (7/3)

2009 Indian Wells Hard QF Nadal 6-2, 6-4

2007 Queen's Club Grass R32 Nadal 6-4, 6-4

2007 French Open R128 Nadal 7-5, 6-3, 6-2

2007 Miami Hard R16 Nadal 6-0, 6-4

World number one and defending champion Nadal, a three-time US Open champion takes on 2009 winner and world number three Del Potro in their third Grand Slam meeting this year.

Nadal cruised past del Potro in straight sets in the semi-finals of Roland Garros on the way to his 11th French Open crown.

Their quarter-final clash at Wimbledon was another affair altogether although it was again Nadal who emerged victorious after rallying from two sets to one down to win in four hours and 48 minutes.

Nadal has won 11 of their 16 meetings, but they are 5-5 on hardcourts including Del Potro's semi-final US Open win in 2009 and Nadal's semi-final win on the way to the title in Flushing Meadows last year.

"He's a great player everywhere," Nadal said of Del Potro. "I will have to play at my highest level to keep having chances of success."

Del Potro's take: "I like to play always with the number one of the world -- doesn't matter the tournament or the conditions or the weather. I just have the chance to play the greatest in this sport, and it's amazing for me."

Kei Nishikori (JPNx21) v Novak Djokovic (SRB x6)

Head to head: Djokovic leads 14-2

2018 Wimbledon Grass QF Djokovic 6-3, 3-6, 6-2, 6-2

2018 Rome Clay QF Djokovic 2-6, 6-1, 6-3

2018 Madrid Clay R64 Djokovic 7-5, 6-4

2016 ATP Finals Hard SF Djokovic 6-1, 6-1

2016 Toronto Hard F Djokovic 6-3, 7-5

2016 Rome Clay SF Djokovic 2-6, 6-4, 7-6 (7/5)

2016 Madrid Clay SF Djokovic 6-3, 7-6 (7/4)

2016 Miami Hard F Djokovic 6-3, 6-3

2016 AUS Open Hard QF Djokovic 6-3, 6-2, 6-4

2015 ATP Finals Hard RR Djokovic 6-1, 6-1

2015 Rome Clay QF Djokovic 6-3, 3-6 6-1

2014 ATP Finals Hard SF Djokovic 6-1, 3-6, 6-0

2014 Paris Hard SF Djokovic 6-2, 6-3

2014 US Open Hard SF Nishikori 6-4, 1-6, 7-6 (7/4), 6-3

2011 Basel Hard SF Nishikori 2-6, 7-6 (7/4), 6-0

2010 French Open Clay R64 Djokovic 6-1, 6-4, 6-4

Djokovic, the 2011 and 2015 US Open champion, will hae a chance to avenge his loss to Nishikori in the semi-finals in 2014 -- when the Japanese player finished runner-up to Marin Cilic.

The good news for Djokovic: Since losing two of his first three matches against Nishikori he has won all 13. That includes a four-set victory in the Wimbledon quarter-finals, where Djokovic burst out of his malaise to win make his first title in more than a year his 13th Grand Slam crown.

Djokovic continued his impressive form with a Cincinnati Masters title in August.

Nishikori, like Djokovic hindered by injury last year, is also on the upswing as his gritty five-set victory over former champion Marin Cilic in the quarter-finals showed.

"He's got one of the best two-handed backhands in the game and very quick," Djokovic said. "Has phenomenal footwork. He's definitely a top-5, top-10 player. I'm expecting a tough one."

Nishikori's take: "I don't have great record against Novak, but always it's been a tough match last couple of years. I've seen a chance, but I haven't been able to make the last step. Especially after coming from injury, I'm enjoying this challenge."