Kyrgios stepped up after the chat with the chair umpire and went on to win the match 4-6, 7-6 (6), 6-3, 6-0 in two hours and 47 minutes, thereby setting up a third-round clash with Federer. "Nick, I know this is not you".
The exchange, and potential impropriety on part of the veteran official, was the central topic of conversation among the sport's chattering class well before Kyrgios finished off the 4-6, 7-6, 6-3, 6-0 victory to book a third-round blockbuster with Roger Federer on Saturday.
Federer has insisted that Lahyani didn't do the right thing by having a mid-match conversation with Kyrgios, who was looking uninterested after being a set and 3-0 down on a hot and humid day in NY.
"She played the game I should have played", said two-time runner-up Wozniacki who has endured a Grand Slam letdown since winning in Australia.
Even before the match had finished tournament officials were launching an investigation into the conduct of the Swedish umpire, looking at whether he had breached the rules governing impartial conduct.
Five-time major champion Sharapova got broken at love to trail 5-4 in the second set.
The USTA initially provided a statement, suggesting that Lahyani didn't do anything particularly wrong. Oh, I'm not feeling so well.
Old pals act: Roger Federer and Benoit Paire embrace, US Open, August 30, 2018.
"The same thing happened to me in Shanghai, before", Kyrgios said.
"I want to help you", Lahyani could be heard saying.
Yawning one second, Kyrgios delivered a return victor the next to break Herbert to get back on serve at 4-5 in the second before clinching the tiebreaker to draw level. "I wasn't really listening to him, but I knew it wasn't a good look", the Australian added.
"I definitely know that I won't be the favourite, the crowd favourite here". I just can tell you from that point Nick was playing much better. He was there for too long.
Kyrgios told the umpire he wasn't feeling well and Lahyani responded, "Let me help you" in what many spectators including ESPN analyst Darren Cahill called an unfair pep talk. "Conversations can change your mindset".
Kyrgios, who has clocked one of the fastest serves at Flushing Meadows this year, won his first-ever match against Federer in 2015 but has lost three in a row since, including one walkover.
"Knowing Mohamed, I really don't think that he meant to do it for any other reason but to really try to help Nick to understand that if he continues doing that, he might get fined or penalty or whatever, or warning".
No. 2 seed Caroline Wozniacki is out of the US Open in the second round, joining No. 1 Simona Halep on the sideline.