Novak Djokovic's strange US Open path took another odd turn Friday as the defending champion defied stultifying humidity and the controversial tactics of Gael Monfils to book a title showdown with Stan Wawrinka.
World number one and defending champion Djokovic prevailed 6-3, 6-2, 3-6, 6-2 in a bizarre semi-final that saw 10th-seeded Monfils roundly booed and accused of not trying.
Third-seeded Wawrinka withstood an early onslaught from sixth-seeded Kei Nishikori of Japan, asserting himself in the later stages to claim a 4-6, 7-5, 6-4, 6-2 victory.
Although Djokovic holds a 19-4 record over Wawrinka, including two victories since the Swiss player shocked him the French Open final last year, Wawrinka welcomed the chance to take him on again.
"To play Novak again it will be very special," he said.
Djokovic admitted he was "completely caught off guard" when Monfils, down 0-5 in the first in 15 minutes, stood lackadaisically in the court and began chipping the ball back.
The strategy paid off as Monfils reeled off three games in a row.
It was Djokovic who emerged with the set, however, and as the Serbian star raced through the second Monfils's interest again appeared to wane.
Monfils said his tactics were a deliberate attempt "to get inside his head".
"I think I should not have allowed him to come back to the match after two sets to love up and 2-love in the third," Djokovic said.
"He started believing in himself. I think the crowd disliked his efforts towards the end of the second set. I think he felt like he needs to step it up and start to play better, which he did."
After giving back an early break in the fourth Djokovic had treatment on his right shoulder, but he broke twice more to close out the win.