Will it be Rafa versus Djoko in Sunday's final?
World No 1 Rafael Nadal faces big-serving third seed Juan Martin del Potro while sixth seed Novak Djokovic meets 21st seed Kei Nishikori bidding to secure a seventh trip to the showcase match at Flushing Meadows.
Form guide for Rafael Nadal ahead of his US Open semi-final clash against Juan Martin del Potro on Friday (prefix number denotes seeding):
1: Rafael Nadal
Age: 32
Height: 1.85 metres
Plays: Left handed
ATP ranking: 1
Grand Slam titles: 17 (Australian Open: 2009; French Open: 2005, 2006, 2007, 2008, 2010, 2011, 2012, 2013, 2014, 2017, 2018; Wimbledon: 2008, 2010; US Open: 2010, 2013, 2017)
Nadal arrived in New York for his title defence after another successful season, having lifted five titles including a record-extending 11th French Open crown.
After two comfortable victories, the 32 year old spent more than seven-and-a-half hours putting away big-hitting opponents Karen Khachanov and Nikoloz Basilashvili.
In the quarter-finals, Nadal failed to win a single game in the opening set against Dominic Thiem, but roared back to claim a five-set thriller.
ROAD TO THE SEMI-FINALS
First round: Beat David Ferrer (Spain) 6-3, 3-4. Ferrer retired
Second round: Beat Vasek Pospisil (Canada) 6-3, 6-4, 6-2
Third Round: Beat 27-Karen Khachanov (Russia) 5-7, 7-5, 7-6(7), 7-6(3)
Fourth Round: Beat Nikoloz Basilashvili (Georgia) 6-3, 6-3, 6-7(6), 6-4
Quarter-finals: Beat 9-Dominic Thiem (Austria) 0-6, 6-4, 7-5, 6-7(4), 7-6(5)
3: Juan Martin del Potro
Age: 29
Height: 1.98 metres
Plays: Right handed
ATP ranking: 3
Grand Slam titles: 1 (US Open 2009)
Del Potro has returned to top form in New York, the scene of his lone Grand Slam victory in 2009, after overcoming wrist injuries that have dogged his career.
The big-serving Argentine cruised through the opening four rounds without dropping a set before overpowering home favourite John Isner in the quarter-finals.
Del Potro has won two titles on hard courts this season, but has suffered defeats by Nadal in his last two major semi-final appearances.
ROAD TO SEMI-FINALS:
First round: Beat Donald Young (US) 6-0, 6-3, 6-4
Second round: Beat Denis Kudla (US) 6-3, 6-1, 7-6(4)
Third Round: Beat 31-Fernando Verdasco (Spain) 7-5, 7-6(6), 6-3
Fourth Round: Beat 20-Borna Coric (Croatia) 6-3, 6-3, 6-1
Quarter-finals: Beat 11-John Isner (US) 6-7(5), 6-3, 7-6(4), 6-2
Form guide for Serbia's Novak Djokovic ahead of his US Open semi-final clash against Japan's Kei Nishikori:
6: Novak Djokovic
Age: 31
Height: 1.88 metres
Plays: Right handed
ATP ranking: 6
Grand Slam titles: 13 (Australian Open: 2008, 2011, 2012, 2013, 2015, 2016; French Open: 2016; Wimbledon: 2011, 2014, 2015, 2018; US Open: 2011, 2015)
Djokovic overcame Australian giant-killer John Millman to reach the semi-finals.
The Serbian returned from a six-month injury absence at the Australian Open this year and had elbow surgery following his last-16 exit in the year's opening major.
He roared back to top form winning the Wimbledon title and is a strong favourite to add a 14th major crown to his collection at Flushing Meadows.
ROAD TO SEMI-FINALS:
First round: Beat Marton Fucsovics (Hungary) 6-3, 3-6, 6-4, 6-0
Second round: Beat Tennys Sandgren (US) 6-1, 6-3, 6-7(2), 6-2
Third Round: Beat 26-Richard Gasquet (France) 6-2, 6-3, 6-3
Fourth Round: Beat Joao Sousa (Portugal) 6-3, 6-4, 6-3
Quarter-finals: Beat John Millman (Australia) 6-3, 6-4, 6-4
21:Kei Nishikori
Age: 28
Height: 1.78 metres
Plays: Right handed
ATP ranking: 19
Grand Slam titles: 0
Best US Open result: Final 2014
Nishikori reached the US Open semi-finals by battling Croatia's Marin Cilic who ended his Grand Slam dream by beating the Japanese in the 2014 final.
Kei has failed to reach another major final after his fine run in New York four years ago, with a wrist injury late last year further hampering his progress.
ROAD TO SEMI-FINALS:
First round: Beat Maximilian Marterer (Germany) 6-2, 6-2, 6-3
Second round: Beat Gael Monfils (France) 6-2, 5-4. Monfils retired.
Third Round: Beat 13-Diego Schwartzman (Argentina) 6-4, 6-4, 5-7, 6-1
Fourth Round: Beat Philipp Kohlschreiber (Germany) 6-3, 6-2, 7-5
Quarter-finals: Beat 7-Marin Cilic (Croatia) 2-6, 6-4, 7-6(5), 4-6, 6-4